Simplified and removed memory leaks from code dealing with frames on Chrome

chrome/ext/background.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
- * Copyright (C) 2006-2013 Eyeo GmbH
+ * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
@@ skipping 195 matching lines @@
   {
     tabs.forEach(function(tab)
     {
       chrome.webNavigation.getAllFrames({tabId: tab.id}, function(details)
       {
         if (details && details.length > 0)
         {
           var frames = framesOfTabs[tab.id] = {__proto__: null};
 
           for (var i = 0; i < details.length; i++)
+            frames[details[i].frameId] = {url: details[i].url, parent: null};
+
+          for (var i = 0; i < details.length; i++)
           {
             var parentFrameId = details[i].parentFrameId;
 
-            frames[details[i].frameId] = {
-              url: details[i].url,
-              parent: parentFrameId != -1 ? frames[parentFrameId] : null

[Wladimir Palant, 2014/03/06 20:58:18]

I don't think that parent frames are guaranteed to be listed earlier, nothing on
it in the docs. I'm afraid two passes are necessary here, with the parent
property being set in the second pass.

[Sebastian Noack, 2014/03/06 21:11:55]

I tested it and it lists the frames top-down. But yes, the documentation doesn't
say anything about that. So what do you suggest? I would also prefer to avoid
adding a second pass. 

[Wladimir Palant, 2014/03/21 14:17:35]

I think a second pass is exactly what we should implement. You *could* do it
without by maintaining queues for each parent that hasn't been seen yet and then
process them when you actually get to that parent. However, this will get
significantly more complicated than a two-pass approach and not necessarily more
efficient (note that this isn't a hot spot so the minimal performance difference
doesn't matter). Add to this that this approach won't be properly testable
because as you already noted - the way this is currently implemented in Chrome
we should never hit an unknown parent.

[Sebastian Noack, 2014/03/31 15:43:44]

Done.

-            };
+            if (parentFrameId != -1)
+              frames[details[i].frameId].parent = frames[parentFrameId];
           }
         }
       });
     });
   });
 
   chrome.webRequest.onBeforeRequest.addListener(function(details)
   {
     if (details.tabId == -1)
       return;
@@ skipping 106 matching lines @@
           {
             if (frames[frameId].url == sender.url)
               return frames[frameId].parent;
           }
 
           return frames[0];
         }
       }
     };
   });
+
+
+  /* Storage */
+
+  ext.storage = localStorage;
 })();