Make Settings explicitly use a cache

The Settings object used by the background page now uses 1 of 3 caches,
depending on the context it is available in:
* localStorage - in the background page
* a copy of localStorage - in non-background extension pages
  (options.html, popup.html, etc.)
* an empty object - in all other pages (where localStorage doesn't point
  to the extension's localStorage object).

For any extension page which is *not* the background page, a copy of
localStorage is used instead of true localStorage:
* Once localStorage is updated by one background page, the others can
  only see the updated copy.
  - Pages with an updated cache can't tell which changes are new, and so
    don't know which postUpdateHooks to run.
* By copying localStorage's contents into a new object, extension pages
  can still access settings synchronously.
  - This is especially important to options.html and popup.html; they
    will not work without it.

1 files changed, 3 insertions, 0 deletions

diff --git a/tests/unit_tests/settings_test.coffee b/tests/unit_tests/settings_test.coffee
index 946a1688..ded7b5f8 100644
--- a/tests/unit_tests/settings_test.coffee
+++ b/tests/unit_tests/settings_test.coffee
@@ -3,6 +3,8 @@ extend global, require "./test_chrome_stubs.js"
 
 extend(global, require "../../lib/utils.js")
 Utils.getCurrentVersion = -> '1.44'
+Utils.isBackgroundPage = -> true
+Utils.isExtensionPage = -> true
 global.localStorage = {}
 extend(global,require "../../lib/settings.js")
 
@@ -10,6 +12,7 @@ context "settings",
 
   setup ->
     stub global, 'localStorage', {}
+    Settings.cache = global.localStorage # Point the settings cache to the new localStorage object.
     Settings.postUpdateHooks = {} # Avoid running update hooks which include calls to outside of settings.
     Settings.init()