Issue 2816 - Restore Preview functionality

chrome/content/actor.jsm

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 let EXPORTED_SYMBOLS = ["shutdown", "getNodeInfo", "togglePreview",
                         "forgetNode"];
 
 const Ci = Components.interfaces;
@@ skipping 19 matching lines @@
 let shutdown = (function()
 {
   let executed = false;
   return function()
   {
     if (!executed)
     {
       executed = true;
       try
       {
         DebuggerServer.removeTabActor(actor);

[Wladimir Palant, 2015/07/31 14:40:04]

This will throw in the content process, I suspect that our way to register the
actor is incorrect. I will investigate this further but in the meantime catching
this error allows the execution to continue - meaning that we won't leave
message handlers attached on shutdown.

[Wladimir Palant, 2015/07/31 15:09:36]

My investigation shows that we are doing everything correctly. This seems to be
a bug in the developer tools, they aren't really testing cleanup it seems (it's
only required for restartless extensions, not built-in actors). Filed
https://bugzilla.mozilla.org/show_bug.cgi?id=1189780 on this, I added a
corresponding comment to the code here.

       }
       catch (e)
       {
+        // The call above will throw in the content process despite succeeding,
+        // see https://bugzilla.mozilla.org/show_bug.cgi?id=1189780.
         Cu.reportError(e);
       }
     }
   }
 })();
 
 function Actor(connection, tabActor)
 {
 }
 
@@ skipping 106 matching lines @@
       // forget this node then.
       forgetNode(nodeID);
     }
   }
 }
 
 function forgetNode(nodeID)
 {
   nodes.delete(nodeID);
 }