DevTools: Make GC button in timeline to fire gc events in all targets

Source/devtools/front_end/timeline/TimelinePanel.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 726 matching lines @@
             return true;
         if (this._recordingInProgress())
             this._stopRecording();
         else
             this._startRecording(true);
         return true;
     },
 
     _garbageCollectButtonClicked: function()
     {
-        HeapProfilerAgent.collectGarbage();
+        var targets = WebInspector.targetManager.targets();
+        for (var i = 0; i < targets.length; ++i)
+            targets[i].heapProfilerAgent().collectGarbage();
     },
 
     _onClearButtonClick: function()
     {
         if (this._tracingModel)
             this._tracingModel.reset();
         this._model.reset();
     },
 
     _onRecordsCleared: function()
@@ skipping 686 matching lines @@
      * @param {!WebInspector.TimelineModel.Record} record
      * @return {boolean}
      */
     accept: function(record)
     {
         return !this._regex || this._uiUtils.testContentMatching(record, this._regex);
     },
 
     __proto__: WebInspector.TimelineModel.Filter.prototype
 }