From ac340e2346247b5cd1878e1a814d4c151df3e892 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Wed, 27 Apr 2016 10:26:24 +0100
Subject: Unregister frame port on onDisconnect.

I seems that we cannot rely upon either the "unload" event in the
content script or the port's onDisconnect handler there to unregister
frames.

To see this, go to a frame-busy page like this one:

- https://www.theguardian.com/technology/2016/apr/26/apple-iphone-first-revenue-decline-13-years

and then navigate to any other simple page (in the same tab).  Navigate
back and forward with `H` and `L`.

If you watch frames registering anf unregistering, almost all of the
frames from the frame-busy page do not unregister.

Here, we unregister frames on onDisconnect in the background page too.

It is possible that this is the source of the problem mentioned as point
1 in this comment:

- https://github.com/philc/vimium/issues/2081#issuecomment-210980903

And for which #2116 is a workaround.
---
 background_scripts/main.coffee | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/background_scripts/main.coffee b/background_scripts/main.coffee
index dca9df7e..9f04d1c0 100644
--- a/background_scripts/main.coffee
+++ b/background_scripts/main.coffee
@@ -289,6 +289,7 @@ for icon in [ENABLED_ICON, DISABLED_ICON, PARTIAL_ICON]
 Frames =
   onConnect: (sender, port) ->
     [tabId, frameId] = [sender.tab.id, sender.frameId]
+    port.onDisconnect.addListener -> Frames.unregisterFrame {tabId, frameId}
     port.postMessage handler: "registerFrameId", chromeFrameId: frameId
 
     # Return our onMessage handler for this port.
@@ -390,9 +391,12 @@ HintCoordinator =
 
   # If an unregistering frame is participating in link-hints mode, then we need to tidy up after it.
   unregisterFrame: (tabId, frameId) ->
-    delete @tabState[tabId]?.ports?[frameId]
-    # We fake "postHintDescriptors" for an unregistering frame.
-    @postHintDescriptors tabId, frameId, hintDescriptors: [] if @tabState[tabId]?.frameIds
+    if @tabState[tabId]?
+      if @tabState[tabId].ports?[frameId]?
+        delete @tabState[tabId].ports[frameId]
+      if @tabState[tabId].frameIds? and frameId in @tabState[tabId].frameIds
+        # We fake an empty "postHintDescriptors" because the frame has gone away.
+        @postHintDescriptors tabId, frameId, hintDescriptors: []
 
 # Port handler mapping
 portHandlers =
-- 
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