From 3aa47a198f2424ba91bb7a8ac07d6b2c53da9698 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Fri, 2 Nov 2012 13:10:33 +0000
Subject: Initial synchronization commit. Synchronization is via
 `chrome.storage.sync.*`; data is cached in `localStorage`.

---
 background_scripts/settings.coffee |  44 ++++++++++--
 background_scripts/sync.coffee     | 136 +++++++++++++++++++++++++++++++++++++
 manifest.json                      |   2 +
 pages/options.coffee               |   8 +--
 4 files changed, 177 insertions(+), 13 deletions(-)
 create mode 100644 background_scripts/sync.coffee

diff --git a/background_scripts/settings.coffee b/background_scripts/settings.coffee
index 0fe1e1bb..64fce308 100644
--- a/background_scripts/settings.coffee
+++ b/background_scripts/settings.coffee
@@ -7,17 +7,49 @@ root.Settings = Settings =
   get: (key) ->
     if (key of localStorage) then JSON.parse(localStorage[key]) else @defaults[key]
 
-  set: (key, value) ->
+  # The doNotSync argument suppresses calls to chrome.storage.sync.* while running unit tests
+  set: (key, value, doNotSync) ->
     # don't store the value if it is equal to the default, so we can change the defaults in the future
-    if (value == @defaults[key])
-      @clear(key)
-    else
-      localStorage[key] = JSON.stringify(value)
+    # warning: this test is always false for settings with numeric default values (such as scrollStepSize)
+    if ( value == @defaults[key] )
+      return @clear(key,doNotSync)
+    # don't update the key/value if it's unchanged; thereby suppressing unnecessary calls to chrome.storage
+    valueJSON = JSON.stringify value
+    if localStorage[key] == valueJSON
+      return localStorage[key]
+    # we have a new value: so update chrome.storage and localStorage
+    root.Sync.set key, valueJSON if root?.Sync?.set
+    localStorage[key] = valueJSON
 
-  clear: (key) -> delete localStorage[key]
+  # The doNotSync argument suppresses calls to chrome.storage.sync.* while running unit tests
+  clear: (key, doNotSync) ->
+    if @has key
+      root.Sync.clear key if root?.Sync?.clear
+      delete localStorage[key]
 
   has: (key) -> key of localStorage
 
+  # the postUpdateHooks handler below is called each time an option changes:
+  #    either from options/options.coffee          (when the options page is saved)
+  #        or from background_scripts/sync.coffee  (when an update propagates from chrome.storage)
+  # 
+  # NOTE:
+  # this has been refactored and renamed from options.coffee(postSaveHooks):
+  #   - refactored because it is now also called from sync.coffee
+  #   - renamed because it is no longer associated only with "Save" operations
+  #
+  postUpdateHooks:
+    keyMappings: (value) ->
+      root.Commands.clearKeyMappingsAndSetDefaults()
+      root.Commands.parseCustomKeyMappings value
+      root.refreshCompletionKeysAfterMappingSave()
+  
+  # postUpdateHooks convenience wrapper
+  doPostUpdateHook: (key, value) ->
+    if @postUpdateHooks[key]
+      @postUpdateHooks[key] value 
+
+
   # options/options.(coffee|html) only handle booleans and strings; therefore
   # all defaults must be booleans or strings
   defaults:
diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
new file mode 100644
index 00000000..d3a18b85
--- /dev/null
+++ b/background_scripts/sync.coffee
@@ -0,0 +1,136 @@
+
+#
+# * Sync.set() and Sync.clear() propagate local changes to chrome.storage.
+# * Sync.listener() listens for changes to chrome.storage and propagates those
+#   changes to localStorage and into vimium's internal state.
+# * Sync.pull() polls chrome.storage at startup, similarly propagating changes
+#   to localStorage and into vimium's internal state.
+#
+# Changes are propagated into vimium's state using the same mechanism that is
+# used when options are changed on the options page.
+#
+# The effect is best-effort synchronization of vimium options/settings between
+# chrome/vimium instances, whenever:
+#   - chrome is logged in to the user's Google account, and
+#   - chrome synchronization is enabled.
+#
+# NOTE:
+#   Values handled within this module are ALWAYS already JSON.stringifed, so
+#   they're always non-empty strings.
+#
+
+console.log ">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>"
+root = exports ? window
+root.Sync = Sync = 
+
+  # ##################
+  # constants
+
+  debug: true
+  storage: chrome.storage.sync
+  doNotSync: [ "settingsVersion", "previousVersion" ]
+
+  init: ->
+    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
+    @pull()
+    @log "Sync.init()"
+
+  # asynchronous fetch from synced storage, called at startup
+  pull: ->
+    @storage.get null, (items) ->
+      Sync.log "pull callback: #{Sync.callbackStatus()}"
+      if not chrome.runtime.lastError
+        for own key, value of items
+          Sync.storeAndPropagate key, value
+
+  # asynchronous message from synced storage
+  listener: (changes, area) ->
+    @log "listener: #{area}"
+    for own key, change of changes
+      @storeAndPropagate key, change.newValue
+  
+  # only ever called from asynchronous synced-storage callbacks (pull and listener)
+  storeAndPropagate: (key, value) ->
+    # must be JSON.stringifed or undefined
+    @checkHaveStringOrUndefined value
+    # ignore, if not accepting this key
+    if not @syncKey key
+       @log "callback ignoring: #{key}"
+       return
+    # ignore, if unchanged
+    if localStorage[key] == value
+       @log "callback unchanged: #{key}"
+       return
+
+    # ok: accept, store and propagate update
+    defaultValue = root.Settings.defaults[key]
+    defaultValueJSON = JSON.stringify(defaultValue) # could cache this to avoid repeated recalculation
+
+    if value && value != defaultValueJSON
+      # key/value has been changed to non-default value at remote instance
+      @log "callback set: #{key}=#{value}"
+      localStorage[key] = value
+      root.Settings.doPostUpdateHook key, JSON.parse(value)
+    else
+      # key has been reset to default value at remote instance
+      @log "callback clear: #{key}=#{value}"
+      delete localStorage[key]
+      root.Settings.doPostUpdateHook key, defaultValue
+
+  # only called synchronously from within vimium, never on a callback
+  # no need to propagate updates into the rest of vimium (because that will already have been handled externally)
+  set: (key, value) ->
+    # value must be JSON.stringifed
+    @checkHaveString value
+    if value
+      if @syncKey key
+        @storage.set @mkKeyValue(key,value), -> Sync.logCallback "DONE set", key
+        @log "set scheduled: #{key}=#{value}"
+    else
+      # unreachable? (because value is a JSON string)
+      @log "UNREACHABLE in Sync.set(): #{key}"
+      @clear key
+
+  # only called synchronously from within vimium, never on a callback
+  # no need to propagate updates into the rest of  vimium (because that will already have been handled by externally)
+  clear: (key) ->
+    if @syncKey key
+      @storage.remove key, -> Sync.logCallback "DONE clear", key
+      @log "clear scheduled: #{key}"
+
+  # ##################
+  # utilities 
+
+  syncKey: (key) ->
+    key not in @doNotSync
+
+  # there has to be a more elegant way to do this!
+  mkKeyValue: (key, value) ->
+    obj = {}
+    obj[key] = value
+    obj
+
+  # debugging messages
+  # disable these by setting root.Sync.debug to anything falsy
+  log: (msg) ->
+    console.log "sync debug: #{msg}" if @debug
+
+  logCallback: (where, key) ->
+    @log "#{where} callback: #{key} #{@callbackStatus()}"
+
+  callbackStatus: ->
+    if chrome.runtime.lastError then "ERROR: #{chrome.runtime.lastError.message}" else "(OK)"
+
+  checkHaveString: (thing) ->
+    if typeof(thing) != "string" or not thing
+      @log "sync.coffee: Yikes! this should be a non-empty string: #{typeof(thing)} #{thing}"
+
+  checkHaveStringOrUndefined: (thing) ->
+    if ( typeof(thing) != "string" and typeof(thing) != "undefined" ) or ( typeof(thing) == "string" and not thing )
+      @log "sync.coffee: Yikes! this should be a non-empty string or undefined: #{typeof(thing)} #{thing}"
+  
+  # end of Sync object
+  # ##################
+
+Sync.init()
+
diff --git a/manifest.json b/manifest.json
index 8de7f009..5692fe75 100644
--- a/manifest.json
+++ b/manifest.json
@@ -11,6 +11,7 @@
       "lib/utils.js",
       "background_scripts/commands.js",
       "lib/clipboard.js",
+      "background_scripts/sync.js",
       "background_scripts/settings.js",
       "background_scripts/completion.js",
       "background_scripts/marks.js",
@@ -23,6 +24,7 @@
     "bookmarks",
     "history",
     "clipboardRead",
+    "storage",
     "<all_urls>"
   ],
   "content_scripts": [
diff --git a/pages/options.coffee b/pages/options.coffee
index 117ce4a6..0aeb8e2d 100644
--- a/pages/options.coffee
+++ b/pages/options.coffee
@@ -8,12 +8,6 @@ editableFields = [ "scrollStepSize", "excludedUrls", "linkHintCharacters", "link
 
 canBeEmptyFields = ["excludedUrls", "keyMappings", "userDefinedLinkHintCss"]
 
-postSaveHooks = keyMappings: (value) ->
-  commands = chrome.extension.getBackgroundPage().Commands
-  commands.clearKeyMappingsAndSetDefaults()
-  commands.parseCustomKeyMappings value
-  chrome.extension.getBackgroundPage().refreshCompletionKeysAfterMappingSave()
-
 document.addEventListener "DOMContentLoaded", ->
   populateOptions()
 
@@ -73,7 +67,7 @@ saveOptions = ->
       bgSettings.set fieldName, fieldValue
     $(fieldName).value = fieldValue
     $(fieldName).setAttribute "savedValue", fieldValue
-    postSaveHooks[fieldName] fieldValue if postSaveHooks[fieldName]
+    bgSettings.doPostUpdateHook fieldName, fieldValue
 
   $("saveOptions").disabled = true
 
-- 
cgit v1.2.3


From 75234c78cf13be08608ccd2b6bcecf2757b199ff Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Fri, 18 Apr 2014 23:09:39 +0100
Subject: Code review of Sync().

---
 background_scripts/settings.coffee |  37 ++++------
 background_scripts/sync.coffee     | 139 +++++++++++++++++--------------------
 2 files changed, 78 insertions(+), 98 deletions(-)

diff --git a/background_scripts/settings.coffee b/background_scripts/settings.coffee
index 64fce308..063287db 100644
--- a/background_scripts/settings.coffee
+++ b/background_scripts/settings.coffee
@@ -7,47 +7,36 @@ root.Settings = Settings =
   get: (key) ->
     if (key of localStorage) then JSON.parse(localStorage[key]) else @defaults[key]
 
-  # The doNotSync argument suppresses calls to chrome.storage.sync.* while running unit tests
   set: (key, value, doNotSync) ->
     # don't store the value if it is equal to the default, so we can change the defaults in the future
-    # warning: this test is always false for settings with numeric default values (such as scrollStepSize)
-    if ( value == @defaults[key] )
-      return @clear(key,doNotSync)
-    # don't update the key/value if it's unchanged; thereby suppressing unnecessary calls to chrome.storage
-    valueJSON = JSON.stringify value
-    if localStorage[key] == valueJSON
-      return localStorage[key]
-    # we have a new value: so update chrome.storage and localStorage
-    root.Sync.set key, valueJSON if root?.Sync?.set
-    localStorage[key] = valueJSON
+    if (value == @defaults[key])
+      @clear(key)
+    else
+      jsonified = JSON.stringify value
+      localStorage[key] = jsonified
+      root.Sync.set key, jsonified
 
-  # The doNotSync argument suppresses calls to chrome.storage.sync.* while running unit tests
-  clear: (key, doNotSync) ->
+  clear: (key) ->
     if @has key
-      root.Sync.clear key if root?.Sync?.clear
       delete localStorage[key]
+    root.Sync.clear key
 
   has: (key) -> key of localStorage
 
-  # the postUpdateHooks handler below is called each time an option changes:
-  #    either from options/options.coffee          (when the options page is saved)
-  #        or from background_scripts/sync.coffee  (when an update propagates from chrome.storage)
-  # 
-  # NOTE:
-  # this has been refactored and renamed from options.coffee(postSaveHooks):
-  #   - refactored because it is now also called from sync.coffee
-  #   - renamed because it is no longer associated only with "Save" operations
+  # postUpdateHooks are called each time an option changes:
+  #   either from options/options.coffee          (when the options page is saved)
+  #       or from background_scripts/sync.coffee  (when an update propagates from chrome.storage)
   #
   postUpdateHooks:
     keyMappings: (value) ->
       root.Commands.clearKeyMappingsAndSetDefaults()
       root.Commands.parseCustomKeyMappings value
       root.refreshCompletionKeysAfterMappingSave()
-  
+
   # postUpdateHooks convenience wrapper
   doPostUpdateHook: (key, value) ->
     if @postUpdateHooks[key]
-      @postUpdateHooks[key] value 
+      @postUpdateHooks[key] value
 
 
   # options/options.(coffee|html) only handle booleans and strings; therefore
diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index d3a18b85..7cb77518 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -1,30 +1,25 @@
 
 #
-# * Sync.set() and Sync.clear() propagate local changes to chrome.storage.
-# * Sync.listener() listens for changes to chrome.storage and propagates those
+# * Sync.set() and Sync.clear() propagate local changes to chrome.storage.sync.
+# * Sync.listener() listens for changes to chrome.storage.sync and propagates those
+#   changes to localStorage and into vimium's internal state.
+# * Sync.pull() polls chrome.storage.sync at startup, similarly propagating
 #   changes to localStorage and into vimium's internal state.
-# * Sync.pull() polls chrome.storage at startup, similarly propagating changes
-#   to localStorage and into vimium's internal state.
 #
-# Changes are propagated into vimium's state using the same mechanism that is
-# used when options are changed on the options page.
+# Changes are propagated into vimium's state using the same mechanism
+# (Settings.doPostUpdateHook) that is used when options are changed on
+# the options page.
 #
 # The effect is best-effort synchronization of vimium options/settings between
-# chrome/vimium instances, whenever:
-#   - chrome is logged in to the user's Google account, and
-#   - chrome synchronization is enabled.
+# chrome/vimium instances.
 #
 # NOTE:
 #   Values handled within this module are ALWAYS already JSON.stringifed, so
 #   they're always non-empty strings.
 #
 
-console.log ">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>"
 root = exports ? window
-root.Sync = Sync = 
-
-  # ##################
-  # constants
+root.Sync = Sync =
 
   debug: true
   storage: chrome.storage.sync
@@ -33,104 +28,100 @@ root.Sync = Sync =
   init: ->
     chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
     @pull()
-    @log "Sync.init()"
 
-  # asynchronous fetch from synced storage, called at startup
+  # Asynchronous fetch from synced storage, called only at startup.
   pull: ->
     @storage.get null, (items) ->
-      Sync.log "pull callback: #{Sync.callbackStatus()}"
-      if not chrome.runtime.lastError
+      if chrome.runtime.lastError is undefined
         for own key, value of items
-          Sync.storeAndPropagate key, value
+          @storeAndPropagate key, value
+      else
+        @log "chrome sync callback for Sync.pull() indicates error"
+        @log chrome.runtime.lastError
 
-  # asynchronous message from synced storage
+  # Asynchronous message from synced storage.
   listener: (changes, area) ->
-    @log "listener: #{area}"
     for own key, change of changes
       @storeAndPropagate key, change.newValue
   
-  # only ever called from asynchronous synced-storage callbacks (pull and listener)
+  # Only ever called from asynchronous synced-storage callbacks (pull and listener).
   storeAndPropagate: (key, value) ->
-    # must be JSON.stringifed or undefined
-    @checkHaveStringOrUndefined value
-    # ignore, if not accepting this key
-    if not @syncKey key
-       @log "callback ignoring: #{key}"
+    # Value must be JSON.stringifed or undefined.
+    if not @checkHaveStringOrUndefined value
+      return
+    # Ignore, we're not accepting this key.
+    if not @isSyncKey key
+       @log "ignoring: #{key}"
        return
-    # ignore, if unchanged
-    if localStorage[key] == value
-       @log "callback unchanged: #{key}"
+    # Ignore, it's unchanged
+    if localStorage[key] is value
+       @log "unchanged: #{key}"
        return
 
-    # ok: accept, store and propagate update
+    # Ok: accept, store and propagate this update.
     defaultValue = root.Settings.defaults[key]
-    defaultValueJSON = JSON.stringify(defaultValue) # could cache this to avoid repeated recalculation
+    defaultValueJSON = JSON.stringify(defaultValue)
 
     if value && value != defaultValueJSON
-      # key/value has been changed to non-default value at remote instance
-      @log "callback set: #{key}=#{value}"
+      # Key/value has been changed to non-default value at remote instance.
+      @log "update: #{key}=#{value}"
       localStorage[key] = value
       root.Settings.doPostUpdateHook key, JSON.parse(value)
     else
-      # key has been reset to default value at remote instance
-      @log "callback clear: #{key}=#{value}"
+      # Key has been reset to default value at remote instance.
+      @log "clear: #{key}"
       delete localStorage[key]
       root.Settings.doPostUpdateHook key, defaultValue
 
-  # only called synchronously from within vimium, never on a callback
-  # no need to propagate updates into the rest of vimium (because that will already have been handled externally)
+  # Only called synchronously from within vimium, never on a callback.
+  # No need to propagate updates into the rest of vimium.
   set: (key, value) ->
-    # value must be JSON.stringifed
-    @checkHaveString value
-    if value
-      if @syncKey key
-        @storage.set @mkKeyValue(key,value), -> Sync.logCallback "DONE set", key
-        @log "set scheduled: #{key}=#{value}"
-    else
-      # unreachable? (because value is a JSON string)
-      @log "UNREACHABLE in Sync.set(): #{key}"
-      @clear key
-
-  # only called synchronously from within vimium, never on a callback
-  # no need to propagate updates into the rest of  vimium (because that will already have been handled by externally)
+    # value has already been JSON.stringifed
+    if not @checkHaveString value
+      return
+    #
+    if @isSyncKey key
+      @storage.set @mkKeyValue(key,value), ->
+        if chrome.runtime.lastError
+          @log "chrome sync callback for Sync.set() indicates error: " + key
+          @log chrome.runtime.lastError
+      @log "set scheduled: #{key}=#{value}"
+
+  # Only called synchronously from within vimium, never on a callback.
   clear: (key) ->
-    if @syncKey key
-      @storage.remove key, -> Sync.logCallback "DONE clear", key
-      @log "clear scheduled: #{key}"
-
-  # ##################
-  # utilities 
-
-  syncKey: (key) ->
+    if @isSyncKey key
+      @storage.remove key, ->
+        if chrome.runtime.lastError
+          @log "chrome sync callback for Sync.clear() indicates error: " + key
+          @log chrome.runtime.lastError
+
+  # Should we synchronize this key?
+  isSyncKey: (key) ->
     key not in @doNotSync
 
-  # there has to be a more elegant way to do this!
+  # There has to be a more elegant way to do this!
   mkKeyValue: (key, value) ->
     obj = {}
     obj[key] = value
     obj
 
-  # debugging messages
-  # disable these by setting root.Sync.debug to anything falsy
+  # Debugging messages.
+  # Disable debugginf by setting root.Sync.debug to anything falsy.
+  # Enabled for the time being (18/4/14) -- smblott.
   log: (msg) ->
-    console.log "sync debug: #{msg}" if @debug
-
-  logCallback: (where, key) ->
-    @log "#{where} callback: #{key} #{@callbackStatus()}"
-
-  callbackStatus: ->
-    if chrome.runtime.lastError then "ERROR: #{chrome.runtime.lastError.message}" else "(OK)"
+    console.log "Sync: #{msg}" if @debug
 
   checkHaveString: (thing) ->
     if typeof(thing) != "string" or not thing
-      @log "sync.coffee: Yikes! this should be a non-empty string: #{typeof(thing)} #{thing}"
+      @log "Sync: Yikes! this should be a non-empty string: #{typeof(thing)} #{thing}"
+      return false
+    return true
 
   checkHaveStringOrUndefined: (thing) ->
     if ( typeof(thing) != "string" and typeof(thing) != "undefined" ) or ( typeof(thing) == "string" and not thing )
-      @log "sync.coffee: Yikes! this should be a non-empty string or undefined: #{typeof(thing)} #{thing}"
+      @log "Sync: Yikes! this should be a non-empty string or undefined: #{typeof(thing)} #{thing}"
+      return false
+    return true
   
-  # end of Sync object
-  # ##################
-
 Sync.init()
 
-- 
cgit v1.2.3


From 654738cb4d566c5e0b2d1e229dd9055403af35f6 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 00:13:36 +0100
Subject: Code review of Sync().

---
 background_scripts/settings.coffee | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/background_scripts/settings.coffee b/background_scripts/settings.coffee
index 063287db..ad89888e 100644
--- a/background_scripts/settings.coffee
+++ b/background_scripts/settings.coffee
@@ -7,14 +7,14 @@ root.Settings = Settings =
   get: (key) ->
     if (key of localStorage) then JSON.parse(localStorage[key]) else @defaults[key]
 
-  set: (key, value, doNotSync) ->
+  set: (key, value) ->
     # don't store the value if it is equal to the default, so we can change the defaults in the future
     if (value == @defaults[key])
       @clear(key)
     else
-      jsonified = JSON.stringify value
-      localStorage[key] = jsonified
-      root.Sync.set key, jsonified
+      jsonValue = JSON.stringify value
+      localStorage[key] = jsonValue
+      root.Sync.set key, jsonValue
 
   clear: (key) ->
     if @has key
-- 
cgit v1.2.3


From 033d353b265fcd4e9963ef232c17d82d7bea43f1 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 07:41:31 +0100
Subject: Settings tests pass, Sync still has an error.

---
 background_scripts/settings.coffee        |  4 ++--
 background_scripts/sync.coffee            |  6 +++---
 tests/unit_tests/settings_test.coffee     | 29 ++++++++++++++++-------------
 tests/unit_tests/test_chrome_stubs.coffee | 11 +++++++++++
 tests/unit_tests/utils_test.coffee        |  3 +++
 5 files changed, 35 insertions(+), 18 deletions(-)
 create mode 100644 tests/unit_tests/test_chrome_stubs.coffee

diff --git a/background_scripts/settings.coffee b/background_scripts/settings.coffee
index ad89888e..f75c1db3 100644
--- a/background_scripts/settings.coffee
+++ b/background_scripts/settings.coffee
@@ -14,12 +14,12 @@ root.Settings = Settings =
     else
       jsonValue = JSON.stringify value
       localStorage[key] = jsonValue
-      root.Sync.set key, jsonValue
+      Sync.set key, jsonValue
 
   clear: (key) ->
     if @has key
       delete localStorage[key]
-    root.Sync.clear key
+    Sync.clear key
 
   has: (key) -> key of localStorage
 
diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 7cb77518..40e0c5c3 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -59,19 +59,19 @@ root.Sync = Sync =
        return
 
     # Ok: accept, store and propagate this update.
-    defaultValue = root.Settings.defaults[key]
+    defaultValue = Settings.defaults[key]
     defaultValueJSON = JSON.stringify(defaultValue)
 
     if value && value != defaultValueJSON
       # Key/value has been changed to non-default value at remote instance.
       @log "update: #{key}=#{value}"
       localStorage[key] = value
-      root.Settings.doPostUpdateHook key, JSON.parse(value)
+      Settings.doPostUpdateHook key, JSON.parse(value)
     else
       # Key has been reset to default value at remote instance.
       @log "clear: #{key}"
       delete localStorage[key]
-      root.Settings.doPostUpdateHook key, defaultValue
+      Settings.doPostUpdateHook key, defaultValue
 
   # Only called synchronously from within vimium, never on a callback.
   # No need to propagate updates into the rest of vimium.
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index b2c5484b..040de285 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -1,30 +1,33 @@
 require "./test_helper.js"
+require "./test_chrome_stubs.js"
 
 extend(global, require "../../lib/utils.js")
 Utils.getCurrentVersion = -> '1.44'
 global.localStorage = {}
-{Settings} = require "../../background_scripts/settings.js"
+
+extend(global,require "../../background_scripts/sync.js")
+extend(global,require "../../background_scripts/settings.js")
 
 context "settings",
 
   setup ->
     stub global, 'localStorage', {}
 
-  should "obtain defaults if no key is stored", ->
-    assert.isFalse Settings.has 'scrollStepSize'
-    assert.equal Settings.get('scrollStepSize'), 60
+should "obtain defaults if no key is stored", ->
+  assert.isFalse Settings.has 'scrollStepSize'
+  assert.equal Settings.get('scrollStepSize'), 60
 
   should "store values", ->
     Settings.set 'scrollStepSize', 20
     assert.equal Settings.get('scrollStepSize'), 20
 
-  should "not store values equal to the default", ->
-    Settings.set 'scrollStepSize', 20
-    assert.isTrue Settings.has 'scrollStepSize'
-    Settings.set 'scrollStepSize', 60
-    assert.isFalse Settings.has 'scrollStepSize'
+should "not store values equal to the default", ->
+  Settings.set 'scrollStepSize', 20
+  assert.isTrue Settings.has 'scrollStepSize'
+  Settings.set 'scrollStepSize', 60
+  assert.isFalse Settings.has 'scrollStepSize'
 
-  should "revert to defaults if no key is stored", ->
-    Settings.set 'scrollStepSize', 20
-    Settings.clear 'scrollStepSize'
-    assert.equal Settings.get('scrollStepSize'), 60
+should "revert to defaults if no key is stored", ->
+  Settings.set 'scrollStepSize', 20
+  Settings.clear 'scrollStepSize'
+  assert.equal Settings.get('scrollStepSize'), 60
diff --git a/tests/unit_tests/test_chrome_stubs.coffee b/tests/unit_tests/test_chrome_stubs.coffee
new file mode 100644
index 00000000..86eef1a1
--- /dev/null
+++ b/tests/unit_tests/test_chrome_stubs.coffee
@@ -0,0 +1,11 @@
+global.chrome ||= {}
+global.chrome.storage ||= {}
+
+global.chrome.storage.onChanged ||=
+  addListener: (changes,area) ->
+
+global.chrome.storage.sync ||=
+  set: (key,value,callback) ->
+  get: (keys,callback) ->
+  remove: (key,callback) ->
+
diff --git a/tests/unit_tests/utils_test.coffee b/tests/unit_tests/utils_test.coffee
index e1aa32c7..8e337d9e 100644
--- a/tests/unit_tests/utils_test.coffee
+++ b/tests/unit_tests/utils_test.coffee
@@ -1,4 +1,7 @@
 require "./test_helper.js"
+require "./test_chrome_stubs.js"
+
+extend(global, require "../../background_scripts/sync.js")
 extend(global, require "../../lib/utils.js")
 extend(global, require "../../background_scripts/settings.js")
 
-- 
cgit v1.2.3


From 91a32f9ebe577aace222f615e17e924018b232e5 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 07:54:09 +0100
Subject: Functional sync.

---
 background_scripts/sync.coffee | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 40e0c5c3..e498172e 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -31,9 +31,10 @@ root.Sync = Sync =
 
   # Asynchronous fetch from synced storage, called only at startup.
   pull: ->
-    @storage.get null, (items) ->
+    @storage.get null, (items) =>
       if chrome.runtime.lastError is undefined
         for own key, value of items
+          @log "pull: #{key} <- #{value}"
           @storeAndPropagate key, value
       else
         @log "chrome sync callback for Sync.pull() indicates error"
@@ -42,6 +43,7 @@ root.Sync = Sync =
   # Asynchronous message from synced storage.
   listener: (changes, area) ->
     for own key, change of changes
+      @log "listener: #{key} <- #{change.newValue}"
       @storeAndPropagate key, change.newValue
   
   # Only ever called from asynchronous synced-storage callbacks (pull and listener).
-- 
cgit v1.2.3


From 8e0bb0a5c749cfae9586dd797d96a0f6233f828c Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 08:01:29 +0100
Subject: Fix indentation and disable sync.log() messages.

---
 background_scripts/sync.coffee        |  4 ++--
 tests/unit_tests/settings_test.coffee | 25 ++++++++++++-------------
 tests/unit_tests/utils_test.coffee    |  3 +--
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index e498172e..afde3e70 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -21,7 +21,7 @@
 root = exports ? window
 root.Sync = Sync =
 
-  debug: true
+  debug: false
   storage: chrome.storage.sync
   doNotSync: [ "settingsVersion", "previousVersion" ]
 
@@ -124,6 +124,6 @@ root.Sync = Sync =
       @log "Sync: Yikes! this should be a non-empty string or undefined: #{typeof(thing)} #{thing}"
       return false
     return true
-  
+
 Sync.init()
 
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 040de285..36a54f11 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -4,7 +4,6 @@ require "./test_chrome_stubs.js"
 extend(global, require "../../lib/utils.js")
 Utils.getCurrentVersion = -> '1.44'
 global.localStorage = {}
-
 extend(global,require "../../background_scripts/sync.js")
 extend(global,require "../../background_scripts/settings.js")
 
@@ -13,21 +12,21 @@ context "settings",
   setup ->
     stub global, 'localStorage', {}
 
-should "obtain defaults if no key is stored", ->
-  assert.isFalse Settings.has 'scrollStepSize'
-  assert.equal Settings.get('scrollStepSize'), 60
+  should "obtain defaults if no key is stored", ->
+    assert.isFalse Settings.has 'scrollStepSize'
+    assert.equal Settings.get('scrollStepSize'), 60
 
   should "store values", ->
     Settings.set 'scrollStepSize', 20
     assert.equal Settings.get('scrollStepSize'), 20
 
-should "not store values equal to the default", ->
-  Settings.set 'scrollStepSize', 20
-  assert.isTrue Settings.has 'scrollStepSize'
-  Settings.set 'scrollStepSize', 60
-  assert.isFalse Settings.has 'scrollStepSize'
+  should "not store values equal to the default", ->
+    Settings.set 'scrollStepSize', 20
+    assert.isTrue Settings.has 'scrollStepSize'
+    Settings.set 'scrollStepSize', 60
+    assert.isFalse Settings.has 'scrollStepSize'
 
-should "revert to defaults if no key is stored", ->
-  Settings.set 'scrollStepSize', 20
-  Settings.clear 'scrollStepSize'
-  assert.equal Settings.get('scrollStepSize'), 60
+  should "revert to defaults if no key is stored", ->
+    Settings.set 'scrollStepSize', 20
+    Settings.clear 'scrollStepSize'
+    assert.equal Settings.get('scrollStepSize'), 60
diff --git a/tests/unit_tests/utils_test.coffee b/tests/unit_tests/utils_test.coffee
index 8e337d9e..09e15353 100644
--- a/tests/unit_tests/utils_test.coffee
+++ b/tests/unit_tests/utils_test.coffee
@@ -1,8 +1,7 @@
 require "./test_helper.js"
 require "./test_chrome_stubs.js"
-
-extend(global, require "../../background_scripts/sync.js")
 extend(global, require "../../lib/utils.js")
+extend(global, require "../../background_scripts/sync.js")
 extend(global, require "../../background_scripts/settings.js")
 
 context "isUrl",
-- 
cgit v1.2.3


From 64f290465aa14478200dc266ccc68b3475352e69 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 08:08:03 +0100
Subject: Add tests for sync.

---
 tests/unit_tests/settings_test.coffee | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 36a54f11..57766c12 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -30,3 +30,15 @@ context "settings",
     Settings.set 'scrollStepSize', 20
     Settings.clear 'scrollStepSize'
     assert.equal Settings.get('scrollStepSize'), 60
+
+  should "remote changes take effect locally, non-default value", ->
+    Settings.set 'scrollStepSize', 20
+    assert.equal Settings.get('scrollStepSize'), 20
+    Sync.listener { scrollStepSize: { newValue: "40" } }
+    assert.equal Settings.get('scrollStepSize'), 40
+
+  should "remote changes take effect locally, default value", ->
+    Settings.set 'scrollStepSize', 20
+    assert.equal Settings.get('scrollStepSize'), 20
+    Sync.listener { scrollStepSize: { newValue: "60" } }
+    assert.isFalse Settings.has 'scrollStepSize'
-- 
cgit v1.2.3


From a2de5078f8d34c2b65b451556aff07a6a41399a5 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 09:44:50 +0100
Subject: Add test cases for "asynchronous" sync.

---
 background_scripts/sync.coffee            |  2 +-
 tests/unit_tests/settings_test.coffee     | 22 ++++++++++++++
 tests/unit_tests/test_chrome_stubs.coffee | 49 +++++++++++++++++++++++++++++--
 3 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index afde3e70..3a829722 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -83,7 +83,7 @@ root.Sync = Sync =
       return
     #
     if @isSyncKey key
-      @storage.set @mkKeyValue(key,value), ->
+      @storage.set @mkKeyValue(key,value), =>
         if chrome.runtime.lastError
           @log "chrome sync callback for Sync.set() indicates error: " + key
           @log chrome.runtime.lastError
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 57766c12..07b96a30 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -42,3 +42,25 @@ context "settings",
     assert.equal Settings.get('scrollStepSize'), 20
     Sync.listener { scrollStepSize: { newValue: "60" } }
     assert.isFalse Settings.has 'scrollStepSize'
+
+  should "remote changes are propagated, non-default value", ->
+    # Prime Sync.
+    Settings.set 'scrollStepSize', 20
+    assert.equal Settings.get('scrollStepSize'), 20
+    # Set a bogus value in localStorage, bypassing Settings and Sync.
+    localStorage['scrollStepSize'] = JSON.stringify(10)
+    assert.equal Settings.get('scrollStepSize'), 10
+    # Pull Sync's version of scrollStepSize, this should reset it to the correct value (20).
+    Sync.pull()
+    assert.equal Settings.get('scrollStepSize'), 20
+
+  should "remote changes are propagated, default value", ->
+    # Prime Sync with a default value.
+    chrome.storage.sync.set { scrollStepSize: JSON.stringify(60) }
+    assert.isFalse Settings.has 'scrollStepSize'
+    # Set a bogus value in localStorage, bypassing Settings and Sync.
+    localStorage['scrollStepSize'] = JSON.stringify(10)
+    assert.equal Settings.get('scrollStepSize'), 10
+    # Pull Sync's version of scrollStepSize, this should delete scrollStepSize in localStorage, because it's a default value.
+    Sync.pull()
+    assert.isFalse Settings.has 'scrollStepSize'
diff --git a/tests/unit_tests/test_chrome_stubs.coffee b/tests/unit_tests/test_chrome_stubs.coffee
index 86eef1a1..f32de24f 100644
--- a/tests/unit_tests/test_chrome_stubs.coffee
+++ b/tests/unit_tests/test_chrome_stubs.coffee
@@ -1,11 +1,56 @@
 global.chrome ||= {}
+global.runtime ||= {}
 global.chrome.storage ||= {}
 
+#
+# This is a stub for chrome.strorage.sync for testing.
+# It does what chrome.storage.sync should do (roughly), but does so synchronously.
+#
+
 global.chrome.storage.onChanged ||=
-  addListener: (changes,area) ->
+  addListener: (func) -> @func = func
+
+  # Fake a callback from chrome.storage.sync.
+  call: (key,value) ->
+    chrome.runtime = { lastError: undefined }
+    if @func
+      @func( @mkKeyValue(key,value), 'synced storage stub' )
+
+  mkKeyValue: (key, value) ->
+    obj = {}
+    obj[key] = { newValue: value }
+    obj
 
 global.chrome.storage.sync ||=
-  set: (key,value,callback) ->
+  store: {}
+
+  set: (items,callback) ->
+    chrome.runtime = { lastError: undefined }
+    for own key, value of items
+      @store[key] = value
+    if callback
+      callback()
+    # Now, generate (supposedly asynchronous) notifications for listeners.
+    for own key, value of items
+      global.chrome.storage.onChanged.call(key,value)
+
   get: (keys,callback) ->
+    chrome.runtime = { lastError: undefined }
+    if keys == null
+      keys = []
+      for own key, value of @store
+        keys.push key
+    items = {}
+    for key in keys
+      items[key] = @store[key]
+    # Now, generate (supposedly asynchronous) callback
+    if callback
+      callback items
+
   remove: (key,callback) ->
+    chrome.runtime = { lastError: undefined }
+    if key of @store
+      delete @store[key]
+    if callback
+      callback()
 
-- 
cgit v1.2.3


From 5ea93cd18611d859867bdd80c44c886d29a7b958 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 10:02:14 +0100
Subject: Add remote sync test for setting cleared.

---
 background_scripts/sync.coffee            | 7 ++++---
 tests/unit_tests/settings_test.coffee     | 9 +++++++++
 tests/unit_tests/test_chrome_stubs.coffee | 9 +++++++++
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 3a829722..3b34c5a6 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -56,7 +56,7 @@ root.Sync = Sync =
        @log "ignoring: #{key}"
        return
     # Ignore, it's unchanged
-    if localStorage[key] is value
+    if key of localStorage and localStorage[key] is value
        @log "unchanged: #{key}"
        return
 
@@ -64,7 +64,7 @@ root.Sync = Sync =
     defaultValue = Settings.defaults[key]
     defaultValueJSON = JSON.stringify(defaultValue)
 
-    if value && value != defaultValueJSON
+    if value and value != defaultValueJSON
       # Key/value has been changed to non-default value at remote instance.
       @log "update: #{key}=#{value}"
       localStorage[key] = value
@@ -72,7 +72,8 @@ root.Sync = Sync =
     else
       # Key has been reset to default value at remote instance.
       @log "clear: #{key}"
-      delete localStorage[key]
+      if key of localStorage
+        delete localStorage[key]
       Settings.doPostUpdateHook key, defaultValue
 
   # Only called synchronously from within vimium, never on a callback.
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 07b96a30..9aec95dd 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -64,3 +64,12 @@ context "settings",
     # Pull Sync's version of scrollStepSize, this should delete scrollStepSize in localStorage, because it's a default value.
     Sync.pull()
     assert.isFalse Settings.has 'scrollStepSize'
+
+  should "remote setting cleared", ->
+    # Prime localStorage.
+    Settings.set 'scrollStepSize', 20
+    assert.equal Settings.get('scrollStepSize'), 20
+    # Prime Sync with a non-default value.
+    chrome.storage.sync.set { scrollStepSize: JSON.stringify(40) }
+    chrome.storage.sync.remove 'scrollStepSize'
+    assert.isFalse Settings.has 'scrollStepSize'
diff --git a/tests/unit_tests/test_chrome_stubs.coffee b/tests/unit_tests/test_chrome_stubs.coffee
index f32de24f..dd8dccf8 100644
--- a/tests/unit_tests/test_chrome_stubs.coffee
+++ b/tests/unit_tests/test_chrome_stubs.coffee
@@ -16,6 +16,13 @@ global.chrome.storage.onChanged ||=
     if @func
       @func( @mkKeyValue(key,value), 'synced storage stub' )
 
+  callEmpty: (key) ->
+    chrome.runtime = { lastError: undefined }
+    if @func
+      items = {}
+      items[key] = {}
+      @func( items, 'synced storage stub' )
+
   mkKeyValue: (key, value) ->
     obj = {}
     obj[key] = { newValue: value }
@@ -53,4 +60,6 @@ global.chrome.storage.sync ||=
       delete @store[key]
     if callback
       callback()
+    # Now, generate (supposedly asynchronous) notification for listeners.
+    global.chrome.storage.onChanged.callEmpty(key)
 
-- 
cgit v1.2.3


From 222d53fe43e34d8d2fd7c2fd859de53cf5fee1f3 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 11:00:32 +0100
Subject: Delay initializing sync until other components have started.

---
 background_scripts/main.coffee        | 3 +++
 background_scripts/sync.coffee        | 6 ++++--
 tests/unit_tests/settings_test.coffee | 1 +
 tests/unit_tests/utils_test.coffee    | 1 +
 4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/background_scripts/main.coffee b/background_scripts/main.coffee
index f564f477..dc853803 100644
--- a/background_scripts/main.coffee
+++ b/background_scripts/main.coffee
@@ -596,3 +596,6 @@ chrome.windows.getAll { populate: true }, (windows) ->
       createScrollPositionHandler = ->
         (response) -> updateScrollPosition(tab, response.scrollX, response.scrollY) if response?
       chrome.tabs.sendMessage(tab.id, { name: "getScrollPosition" }, createScrollPositionHandler())
+
+# Start pulling changes from synchrized storage.
+Sync.init()
diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 3b34c5a6..b1ccb696 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -25,9 +25,11 @@ root.Sync = Sync =
   storage: chrome.storage.sync
   doNotSync: [ "settingsVersion", "previousVersion" ]
 
+  register: ->
+    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
+
   init: ->
     chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
-    @pull()
 
   # Asynchronous fetch from synced storage, called only at startup.
   pull: ->
@@ -126,5 +128,5 @@ root.Sync = Sync =
       return false
     return true
 
-Sync.init()
+Sync.register()
 
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 9aec95dd..4b6f3498 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -6,6 +6,7 @@ Utils.getCurrentVersion = -> '1.44'
 global.localStorage = {}
 extend(global,require "../../background_scripts/sync.js")
 extend(global,require "../../background_scripts/settings.js")
+Sync.init()
 
 context "settings",
 
diff --git a/tests/unit_tests/utils_test.coffee b/tests/unit_tests/utils_test.coffee
index 09e15353..356bc39f 100644
--- a/tests/unit_tests/utils_test.coffee
+++ b/tests/unit_tests/utils_test.coffee
@@ -3,6 +3,7 @@ require "./test_chrome_stubs.js"
 extend(global, require "../../lib/utils.js")
 extend(global, require "../../background_scripts/sync.js")
 extend(global, require "../../background_scripts/settings.js")
+Sync.init()
 
 context "isUrl",
   should "accept valid URLs", ->
-- 
cgit v1.2.3


From b8c501ee2e4f85ef8307ec27f39ea98fe0779a6c Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 11:07:30 +0100
Subject: Test that all stored settings are JSONified.

---
 tests/unit_tests/settings_test.coffee | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 4b6f3498..5d24c7f2 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -13,6 +13,10 @@ context "settings",
   setup ->
     stub global, 'localStorage', {}
 
+  should "all settings stored in localStorage must be JSONified strings", ->
+    Settings.set 'dummy', ""
+    assert.equal localStorage.dummy, '""'
+
   should "obtain defaults if no key is stored", ->
     assert.isFalse Settings.has 'scrollStepSize'
     assert.equal Settings.get('scrollStepSize'), 60
-- 
cgit v1.2.3


From 0ff5b7a8ead8ad9051f0a9ba4a9667f07c9c38ac Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 11:19:59 +0100
Subject: Comments for philc.

---
 background_scripts/sync.coffee | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index b1ccb696..dfa260b5 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -1,4 +1,3 @@
-
 #
 # * Sync.set() and Sync.clear() propagate local changes to chrome.storage.sync.
 # * Sync.listener() listens for changes to chrome.storage.sync and propagates those
@@ -21,6 +20,12 @@
 root = exports ? window
 root.Sync = Sync =
 
+  # 19/4/14:
+  # Leave logging statements in, but disable debugging.
+  # We may need to come back to this, so removing logging now would be premature.
+  # However, if users have problems, they are unlikely to notice and make sense of console logs on
+  # background pages.  So disable it, by default.
+  # For genuine errors, we call console.log directly.
   debug: false
   storage: chrome.storage.sync
   doNotSync: [ "settingsVersion", "previousVersion" ]
@@ -34,13 +39,14 @@ root.Sync = Sync =
   # Asynchronous fetch from synced storage, called only at startup.
   pull: ->
     @storage.get null, (items) =>
+      # Chrome sets chrome.runtime.lastError if there is an error.
       if chrome.runtime.lastError is undefined
         for own key, value of items
           @log "pull: #{key} <- #{value}"
           @storeAndPropagate key, value
       else
-        @log "chrome sync callback for Sync.pull() indicates error"
-        @log chrome.runtime.lastError
+        console.log "chrome sync callback for Sync.pull() indicates error"
+        console.log chrome.runtime.lastError
 
   # Asynchronous message from synced storage.
   listener: (changes, area) ->
@@ -87,18 +93,20 @@ root.Sync = Sync =
     #
     if @isSyncKey key
       @storage.set @mkKeyValue(key,value), =>
+        # Chrome sets chrome.runtime.lastError if there is an error.
         if chrome.runtime.lastError
-          @log "chrome sync callback for Sync.set() indicates error: " + key
-          @log chrome.runtime.lastError
+          console.log "chrome sync callback for Sync.set() indicates error: " + key
+          console.log chrome.runtime.lastError
       @log "set scheduled: #{key}=#{value}"
 
   # Only called synchronously from within vimium, never on a callback.
   clear: (key) ->
     if @isSyncKey key
-      @storage.remove key, ->
+      @storage.remove key, =>
+        # Chrome sets chrome.runtime.lastError if there is an error.
         if chrome.runtime.lastError
-          @log "chrome sync callback for Sync.clear() indicates error: " + key
-          @log chrome.runtime.lastError
+          console.log "chrome sync callback for Sync.clear() indicates error: " + key
+          console.log chrome.runtime.lastError
 
   # Should we synchronize this key?
   isSyncKey: (key) ->
@@ -129,4 +137,3 @@ root.Sync = Sync =
     return true
 
 Sync.register()
-
-- 
cgit v1.2.3


From 5398abdb0af3b0d7938c8b34bfda762c5995d427 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 14:27:34 +0100
Subject: Fix sync.init.

---
 background_scripts/sync.coffee | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index dfa260b5..4413a748 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -34,7 +34,7 @@ root.Sync = Sync =
     chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
 
   init: ->
-    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
+    @pull()
 
   # Asynchronous fetch from synced storage, called only at startup.
   pull: ->
-- 
cgit v1.2.3


From 2f343bacd7567cb51901b7f8b54f224ea2f011b2 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 14:49:45 +0100
Subject: Code review, clean up.

---
 background_scripts/sync.coffee | 52 +++++++++++-------------------------------
 1 file changed, 13 insertions(+), 39 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 4413a748..454aa6fd 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -45,67 +45,56 @@ root.Sync = Sync =
           @log "pull: #{key} <- #{value}"
           @storeAndPropagate key, value
       else
-        console.log "chrome sync callback for Sync.pull() indicates error"
+        console.log "callback for Sync.pull() indicates error"
         console.log chrome.runtime.lastError
 
   # Asynchronous message from synced storage.
   listener: (changes, area) ->
     for own key, change of changes
       @log "listener: #{key} <- #{change.newValue}"
-      @storeAndPropagate key, change.newValue
+      @storeAndPropagate key, change?.newValue
   
   # Only ever called from asynchronous synced-storage callbacks (pull and listener).
   storeAndPropagate: (key, value) ->
-    # Value must be JSON.stringifed or undefined.
-    if not @checkHaveStringOrUndefined value
-      return
-    # Ignore, we're not accepting this key.
-    if not @isSyncKey key
-       @log "ignoring: #{key}"
-       return
-    # Ignore, it's unchanged
-    if key of localStorage and localStorage[key] is value
-       @log "unchanged: #{key}"
-       return
+    return if not key of Settings.defaults
+    return if not @isSyncKey key
+    return if value and key of localStorage and localStorage[key] is value
 
-    # Ok: accept, store and propagate this update.
+    # Ok: store and propagate this update.
     defaultValue = Settings.defaults[key]
     defaultValueJSON = JSON.stringify(defaultValue)
 
     if value and value != defaultValueJSON
       # Key/value has been changed to non-default value at remote instance.
-      @log "update: #{key}=#{value}"
+      @log "storeAndPropagate update: #{key}=#{value}"
       localStorage[key] = value
       Settings.doPostUpdateHook key, JSON.parse(value)
     else
       # Key has been reset to default value at remote instance.
-      @log "clear: #{key}"
+      @log "storeAndPropagate clear: #{key}"
       if key of localStorage
         delete localStorage[key]
       Settings.doPostUpdateHook key, defaultValue
 
   # Only called synchronously from within vimium, never on a callback.
-  # No need to propagate updates into the rest of vimium.
+  # No need to propagate updates to the rest of vimium, that's already been done.
   set: (key, value) ->
-    # value has already been JSON.stringifed
-    if not @checkHaveString value
-      return
-    #
     if @isSyncKey key
+      @log "set scheduled: #{key}=#{value}"
       @storage.set @mkKeyValue(key,value), =>
         # Chrome sets chrome.runtime.lastError if there is an error.
         if chrome.runtime.lastError
-          console.log "chrome sync callback for Sync.set() indicates error: " + key
+          console.log "callback for Sync.set() indicates error: #{key} <- #{value}"
           console.log chrome.runtime.lastError
-      @log "set scheduled: #{key}=#{value}"
 
   # Only called synchronously from within vimium, never on a callback.
   clear: (key) ->
     if @isSyncKey key
+      @log "clear scheduled: #{key}"
       @storage.remove key, =>
         # Chrome sets chrome.runtime.lastError if there is an error.
         if chrome.runtime.lastError
-          console.log "chrome sync callback for Sync.clear() indicates error: " + key
+          console.log "for Sync.clear() indicates error: #{key}"
           console.log chrome.runtime.lastError
 
   # Should we synchronize this key?
@@ -118,22 +107,7 @@ root.Sync = Sync =
     obj[key] = value
     obj
 
-  # Debugging messages.
-  # Disable debugginf by setting root.Sync.debug to anything falsy.
-  # Enabled for the time being (18/4/14) -- smblott.
   log: (msg) ->
     console.log "Sync: #{msg}" if @debug
 
-  checkHaveString: (thing) ->
-    if typeof(thing) != "string" or not thing
-      @log "Sync: Yikes! this should be a non-empty string: #{typeof(thing)} #{thing}"
-      return false
-    return true
-
-  checkHaveStringOrUndefined: (thing) ->
-    if ( typeof(thing) != "string" and typeof(thing) != "undefined" ) or ( typeof(thing) == "string" and not thing )
-      @log "Sync: Yikes! this should be a non-empty string or undefined: #{typeof(thing)} #{thing}"
-      return false
-    return true
-
 Sync.register()
-- 
cgit v1.2.3


From 4083ee6423c10c34c1d0a3fa48e8f4d79c8615df Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 14:52:38 +0100
Subject: Clean up initialization.

---
 background_scripts/sync.coffee | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 454aa6fd..1c6c7fb6 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -30,10 +30,9 @@ root.Sync = Sync =
   storage: chrome.storage.sync
   doNotSync: [ "settingsVersion", "previousVersion" ]
 
-  register: ->
-    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
-
+  # This is called in main().
   init: ->
+    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
     @pull()
 
   # Asynchronous fetch from synced storage, called only at startup.
@@ -110,4 +109,3 @@ root.Sync = Sync =
   log: (msg) ->
     console.log "Sync: #{msg}" if @debug
 
-Sync.register()
-- 
cgit v1.2.3


From a9cec9742115a098a031ae7f946eb7bb93648ecd Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sat, 19 Apr 2014 15:17:43 +0100
Subject: Add a couple more test cases for Sync.

---
 tests/unit_tests/settings_test.coffee | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 5d24c7f2..dd2815f0 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -78,3 +78,16 @@ context "settings",
     chrome.storage.sync.set { scrollStepSize: JSON.stringify(40) }
     chrome.storage.sync.remove 'scrollStepSize'
     assert.isFalse Settings.has 'scrollStepSize'
+
+  should "trigger a postUpdateHook", ->
+    message = "Hello World"
+    # Install a bogus update hook for an existing setting.
+    Settings.postUpdateHooks['scrollStepSize'] = (value) -> Sync.message = value
+    chrome.storage.sync.set { scrollStepSize: JSON.stringify(message) }
+    # Was the update hook triggered?
+    assert.equal message, Sync.message
+
+  should "sync a key which is not a setting", ->
+    # There is nothing to test, here.  It's purpose is just to ensure that, should additional settings be
+    # added in future, then the Sync won't cause unexpected crashes.
+    chrome.storage.sync.set { notASetting: JSON.stringify("notAUsefullValue") }
-- 
cgit v1.2.3


From db65721aa67b2de75b1e279f01e721676e83b448 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Sun, 27 Apr 2014 11:52:30 +0100
Subject: Response to @philc's comments regarding sync.

---
 background_scripts/main.coffee            |   2 +-
 background_scripts/settings.coffee        |  13 ++--
 background_scripts/sync.coffee            |  50 ++++++-------
 pages/options.coffee                      |   2 +-
 tests/unit_tests/settings_test.coffee     |  45 ++++--------
 tests/unit_tests/test_chrome_stubs.coffee | 114 ++++++++++++++----------------
 6 files changed, 97 insertions(+), 129 deletions(-)

diff --git a/background_scripts/main.coffee b/background_scripts/main.coffee
index dc853803..5147aec2 100644
--- a/background_scripts/main.coffee
+++ b/background_scripts/main.coffee
@@ -597,5 +597,5 @@ chrome.windows.getAll { populate: true }, (windows) ->
         (response) -> updateScrollPosition(tab, response.scrollX, response.scrollY) if response?
       chrome.tabs.sendMessage(tab.id, { name: "getScrollPosition" }, createScrollPositionHandler())
 
-# Start pulling changes from synchrized storage.
+# Start pulling changes from synchronized storage.
 Sync.init()
diff --git a/background_scripts/settings.coffee b/background_scripts/settings.coffee
index f75c1db3..73a7a04b 100644
--- a/background_scripts/settings.coffee
+++ b/background_scripts/settings.coffee
@@ -23,10 +23,9 @@ root.Settings = Settings =
 
   has: (key) -> key of localStorage
 
-  # postUpdateHooks are called each time an option changes:
-  #   either from options/options.coffee          (when the options page is saved)
-  #       or from background_scripts/sync.coffee  (when an update propagates from chrome.storage)
-  #
+  # for settings which require action when their value changes, add hooks here
+  # called from options/options.coffee (when the options page is saved), and from background_scripts/sync.coffee (when
+  # an update propagates from chrome.storage.sync).
   postUpdateHooks:
     keyMappings: (value) ->
       root.Commands.clearKeyMappingsAndSetDefaults()
@@ -34,10 +33,8 @@ root.Settings = Settings =
       root.refreshCompletionKeysAfterMappingSave()
 
   # postUpdateHooks convenience wrapper
-  doPostUpdateHook: (key, value) ->
-    if @postUpdateHooks[key]
-      @postUpdateHooks[key] value
-
+  performPostUpdateHook: (key, value) ->
+    @postUpdateHooks[key] value if @postUpdateHooks[key]
 
   # options/options.(coffee|html) only handle booleans and strings; therefore
   # all defaults must be booleans or strings
diff --git a/background_scripts/sync.coffee b/background_scripts/sync.coffee
index 1c6c7fb6..56c74b81 100644
--- a/background_scripts/sync.coffee
+++ b/background_scripts/sync.coffee
@@ -1,12 +1,12 @@
 #
 # * Sync.set() and Sync.clear() propagate local changes to chrome.storage.sync.
-# * Sync.listener() listens for changes to chrome.storage.sync and propagates those
+# * Sync.handleStorageUpdate() listens for changes to chrome.storage.sync and propagates those
 #   changes to localStorage and into vimium's internal state.
-# * Sync.pull() polls chrome.storage.sync at startup, similarly propagating
+# * Sync.fetchAsync() polls chrome.storage.sync at startup, similarly propagating
 #   changes to localStorage and into vimium's internal state.
 #
 # Changes are propagated into vimium's state using the same mechanism
-# (Settings.doPostUpdateHook) that is used when options are changed on
+# (Settings.performPostUpdateHook) that is used when options are changed on
 # the options page.
 #
 # The effect is best-effort synchronization of vimium options/settings between
@@ -26,40 +26,38 @@ root.Sync = Sync =
   # However, if users have problems, they are unlikely to notice and make sense of console logs on
   # background pages.  So disable it, by default.
   # For genuine errors, we call console.log directly.
-  debug: false
+  debug: true
   storage: chrome.storage.sync
   doNotSync: [ "settingsVersion", "previousVersion" ]
 
-  # This is called in main().
+  # This is called in main.coffee.
   init: ->
-    chrome.storage.onChanged.addListener (changes, area) -> Sync.listener changes, area
-    @pull()
+    chrome.storage.onChanged.addListener (changes, area) -> Sync.handleStorageUpdate changes, area
+    @fetchAsync()
 
   # Asynchronous fetch from synced storage, called only at startup.
-  pull: ->
+  fetchAsync: ->
     @storage.get null, (items) =>
       # Chrome sets chrome.runtime.lastError if there is an error.
       if chrome.runtime.lastError is undefined
         for own key, value of items
-          @log "pull: #{key} <- #{value}"
+          @log "fetchAsync: #{key} <- #{value}"
           @storeAndPropagate key, value
       else
-        console.log "callback for Sync.pull() indicates error"
+        console.log "callback for Sync.fetchAsync() indicates error"
         console.log chrome.runtime.lastError
 
   # Asynchronous message from synced storage.
-  listener: (changes, area) ->
+  handleStorageUpdate: (changes, area) ->
     for own key, change of changes
-      @log "listener: #{key} <- #{change.newValue}"
+      @log "handleStorageUpdate: #{key} <- #{change.newValue}"
       @storeAndPropagate key, change?.newValue
   
-  # Only ever called from asynchronous synced-storage callbacks (pull and listener).
+  # Only ever called from asynchronous synced-storage callbacks (fetchAsync and handleStorageUpdate).
   storeAndPropagate: (key, value) ->
     return if not key of Settings.defaults
-    return if not @isSyncKey key
+    return if not @shouldSyncKey key
     return if value and key of localStorage and localStorage[key] is value
-
-    # Ok: store and propagate this update.
     defaultValue = Settings.defaults[key]
     defaultValueJSON = JSON.stringify(defaultValue)
 
@@ -67,20 +65,22 @@ root.Sync = Sync =
       # Key/value has been changed to non-default value at remote instance.
       @log "storeAndPropagate update: #{key}=#{value}"
       localStorage[key] = value
-      Settings.doPostUpdateHook key, JSON.parse(value)
+      Settings.performPostUpdateHook key, JSON.parse(value)
     else
       # Key has been reset to default value at remote instance.
       @log "storeAndPropagate clear: #{key}"
       if key of localStorage
         delete localStorage[key]
-      Settings.doPostUpdateHook key, defaultValue
+      Settings.performPostUpdateHook key, defaultValue
 
   # Only called synchronously from within vimium, never on a callback.
   # No need to propagate updates to the rest of vimium, that's already been done.
   set: (key, value) ->
-    if @isSyncKey key
+    if @shouldSyncKey key
       @log "set scheduled: #{key}=#{value}"
-      @storage.set @mkKeyValue(key,value), =>
+      key_value = {}
+      key_value[key] = value
+      @storage.set key_value, =>
         # Chrome sets chrome.runtime.lastError if there is an error.
         if chrome.runtime.lastError
           console.log "callback for Sync.set() indicates error: #{key} <- #{value}"
@@ -88,7 +88,7 @@ root.Sync = Sync =
 
   # Only called synchronously from within vimium, never on a callback.
   clear: (key) ->
-    if @isSyncKey key
+    if @shouldSyncKey key
       @log "clear scheduled: #{key}"
       @storage.remove key, =>
         # Chrome sets chrome.runtime.lastError if there is an error.
@@ -97,15 +97,9 @@ root.Sync = Sync =
           console.log chrome.runtime.lastError
 
   # Should we synchronize this key?
-  isSyncKey: (key) ->
+  shouldSyncKey: (key) ->
     key not in @doNotSync
 
-  # There has to be a more elegant way to do this!
-  mkKeyValue: (key, value) ->
-    obj = {}
-    obj[key] = value
-    obj
-
   log: (msg) ->
     console.log "Sync: #{msg}" if @debug
 
diff --git a/pages/options.coffee b/pages/options.coffee
index 0aeb8e2d..34696f68 100644
--- a/pages/options.coffee
+++ b/pages/options.coffee
@@ -67,7 +67,7 @@ saveOptions = ->
       bgSettings.set fieldName, fieldValue
     $(fieldName).value = fieldValue
     $(fieldName).setAttribute "savedValue", fieldValue
-    bgSettings.doPostUpdateHook fieldName, fieldValue
+    bgSettings.performPostUpdateHook fieldName, fieldValue
 
   $("saveOptions").disabled = true
 
diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index dd2815f0..25bb3628 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -13,7 +13,7 @@ context "settings",
   setup ->
     stub global, 'localStorage', {}
 
-  should "all settings stored in localStorage must be JSONified strings", ->
+  should "save settings in localStorage as JSONified strings", ->
     Settings.set 'dummy', ""
     assert.equal localStorage.dummy, '""'
 
@@ -36,58 +36,39 @@ context "settings",
     Settings.clear 'scrollStepSize'
     assert.equal Settings.get('scrollStepSize'), 60
 
-  should "remote changes take effect locally, non-default value", ->
+  should "propagate non-default value via synced storage listener", ->
     Settings.set 'scrollStepSize', 20
     assert.equal Settings.get('scrollStepSize'), 20
-    Sync.listener { scrollStepSize: { newValue: "40" } }
+    Sync.handleStorageUpdate { scrollStepSize: { newValue: "40" } }
     assert.equal Settings.get('scrollStepSize'), 40
 
-  should "remote changes take effect locally, default value", ->
+  should "propagate default value via synced storage listener", ->
     Settings.set 'scrollStepSize', 20
     assert.equal Settings.get('scrollStepSize'), 20
-    Sync.listener { scrollStepSize: { newValue: "60" } }
+    Sync.handleStorageUpdate { scrollStepSize: { newValue: "60" } }
     assert.isFalse Settings.has 'scrollStepSize'
 
-  should "remote changes are propagated, non-default value", ->
-    # Prime Sync.
-    Settings.set 'scrollStepSize', 20
-    assert.equal Settings.get('scrollStepSize'), 20
-    # Set a bogus value in localStorage, bypassing Settings and Sync.
-    localStorage['scrollStepSize'] = JSON.stringify(10)
-    assert.equal Settings.get('scrollStepSize'), 10
-    # Pull Sync's version of scrollStepSize, this should reset it to the correct value (20).
-    Sync.pull()
+  should "propagate non-default values from synced storage", ->
+    chrome.storage.sync.set { scrollStepSize: JSON.stringify(20) }
+    Sync.fetchAsync()
     assert.equal Settings.get('scrollStepSize'), 20
 
-  should "remote changes are propagated, default value", ->
-    # Prime Sync with a default value.
+  should "propagate default values from synced storage", ->
+    Settings.set 'scrollStepSize', 20
     chrome.storage.sync.set { scrollStepSize: JSON.stringify(60) }
-    assert.isFalse Settings.has 'scrollStepSize'
-    # Set a bogus value in localStorage, bypassing Settings and Sync.
-    localStorage['scrollStepSize'] = JSON.stringify(10)
-    assert.equal Settings.get('scrollStepSize'), 10
-    # Pull Sync's version of scrollStepSize, this should delete scrollStepSize in localStorage, because it's a default value.
-    Sync.pull()
+    Sync.fetchAsync()
     assert.isFalse Settings.has 'scrollStepSize'
 
-  should "remote setting cleared", ->
-    # Prime localStorage.
+  should "clear a setting from synced storage", ->
     Settings.set 'scrollStepSize', 20
-    assert.equal Settings.get('scrollStepSize'), 20
-    # Prime Sync with a non-default value.
-    chrome.storage.sync.set { scrollStepSize: JSON.stringify(40) }
     chrome.storage.sync.remove 'scrollStepSize'
     assert.isFalse Settings.has 'scrollStepSize'
 
   should "trigger a postUpdateHook", ->
     message = "Hello World"
-    # Install a bogus update hook for an existing setting.
     Settings.postUpdateHooks['scrollStepSize'] = (value) -> Sync.message = value
     chrome.storage.sync.set { scrollStepSize: JSON.stringify(message) }
-    # Was the update hook triggered?
     assert.equal message, Sync.message
 
-  should "sync a key which is not a setting", ->
-    # There is nothing to test, here.  It's purpose is just to ensure that, should additional settings be
-    # added in future, then the Sync won't cause unexpected crashes.
+  should "sync a key which is not a known setting (without crashing)", ->
     chrome.storage.sync.set { notASetting: JSON.stringify("notAUsefullValue") }
diff --git a/tests/unit_tests/test_chrome_stubs.coffee b/tests/unit_tests/test_chrome_stubs.coffee
index dd8dccf8..e9c48f31 100644
--- a/tests/unit_tests/test_chrome_stubs.coffee
+++ b/tests/unit_tests/test_chrome_stubs.coffee
@@ -1,65 +1,61 @@
-global.chrome ||= {}
-global.runtime ||= {}
-global.chrome.storage ||= {}
 
 #
 # This is a stub for chrome.strorage.sync for testing.
 # It does what chrome.storage.sync should do (roughly), but does so synchronously.
 #
 
-global.chrome.storage.onChanged ||=
-  addListener: (func) -> @func = func
-
-  # Fake a callback from chrome.storage.sync.
-  call: (key,value) ->
-    chrome.runtime = { lastError: undefined }
-    if @func
-      @func( @mkKeyValue(key,value), 'synced storage stub' )
-
-  callEmpty: (key) ->
-    chrome.runtime = { lastError: undefined }
-    if @func
-      items = {}
-      items[key] = {}
-      @func( items, 'synced storage stub' )
-
-  mkKeyValue: (key, value) ->
-    obj = {}
-    obj[key] = { newValue: value }
-    obj
-
-global.chrome.storage.sync ||=
-  store: {}
-
-  set: (items,callback) ->
-    chrome.runtime = { lastError: undefined }
-    for own key, value of items
-      @store[key] = value
-    if callback
-      callback()
-    # Now, generate (supposedly asynchronous) notifications for listeners.
-    for own key, value of items
-      global.chrome.storage.onChanged.call(key,value)
-
-  get: (keys,callback) ->
-    chrome.runtime = { lastError: undefined }
-    if keys == null
-      keys = []
-      for own key, value of @store
-        keys.push key
-    items = {}
-    for key in keys
-      items[key] = @store[key]
-    # Now, generate (supposedly asynchronous) callback
-    if callback
-      callback items
-
-  remove: (key,callback) ->
-    chrome.runtime = { lastError: undefined }
-    if key of @store
-      delete @store[key]
-    if callback
-      callback()
-    # Now, generate (supposedly asynchronous) notification for listeners.
-    global.chrome.storage.onChanged.callEmpty(key)
-
+global.chrome =
+  runtime: {}
+
+  storage:
+
+    # chrome.storage.onChanged
+    onChanged:
+      addListener: (func) -> @func = func
+
+      # Fake a callback from chrome.storage.sync.
+      call: (key, value) ->
+        chrome.runtime = { lastError: undefined }
+        key_value = {}
+        key_value[key] = { newValue: value }
+        @func(key_value,'synced storage stub') if @func
+
+      callEmpty: (key) ->
+        chrome.runtime = { lastError: undefined }
+        if @func
+          items = {}
+          items[key] = {}
+          @func(items,'synced storage stub')
+
+    # chrome.storage.sync
+    sync:
+      store: {}
+
+      set: (items, callback) ->
+        chrome.runtime = { lastError: undefined }
+        for own key, value of items
+          @store[key] = value
+        callback() if callback
+        # Now, generate (supposedly asynchronous) notifications for listeners.
+        for own key, value of items
+          global.chrome.storage.onChanged.call(key,value)
+
+      get: (keys, callback) ->
+        chrome.runtime = { lastError: undefined }
+        if keys == null
+          keys = []
+          for own key, value of @store
+            keys.push key
+        items = {}
+        for key in keys
+          items[key] = @store[key]
+        # Now, generate (supposedly asynchronous) callback
+        callback items if callback
+
+      remove: (key, callback) ->
+        chrome. runtime = { lastError: undefined }
+        if key of @store
+          delete @store[key]
+        callback() if callback
+        # Now, generate (supposedly asynchronous) notification for listeners.
+        global.chrome.storage.onChanged.callEmpty(key)
-- 
cgit v1.2.3