DevTools: make paint profiler target-aware

Source/devtools/front_end/timeline/TimelineFrameModel.js

 /*
  * Copyright (C) 2013 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 294 matching lines @@
     },
 
     /**
      * @param {?WebInspector.TimelineModel.Record} programRecord
      * @param {!WebInspector.TimelineModel.Record} record
      */
     _addMainThreadRecord: function(programRecord, record)
     {
         var recordTypes = WebInspector.TimelineModel.RecordType;
         if (record.type() === recordTypes.UpdateLayerTree && record.data()["layerTree"])
-            this.handleLayerTreeSnapshot(new WebInspector.DeferredAgentLayerTree(this.target(), record.data()["layerTree"]));
+            this.handleLayerTreeSnapshot(new WebInspector.DeferredAgentLayerTree(this.target().weakReference(), record.data()["layerTree"]));
         if (!this._hasThreadedCompositing) {
             if (record.type() === recordTypes.BeginFrame)
                 this._startMainThreadFrame(record.startTime());
 
             if (!this._lastFrame)
                 return;
 
             this._lastFrame._addTimeFromRecord(record);
 
             // Account for "other" time at the same time as the first child.
@@ skipping 84 matching lines @@
     },
 
     /**
      * @param {!WebInspector.TracingModel.Event} event
      */
     _addBackgroundTraceEvent: function(event)
     {
         var eventNames = WebInspector.TracingTimelineModel.RecordType;
 
         if (event.phase === WebInspector.TracingModel.Phase.SnapshotObject && event.name === eventNames.LayerTreeHostImplSnapshot && parseInt(event.id, 0) === this._layerTreeId) {
-            this.handleLayerTreeSnapshot(new WebInspector.DeferredTracingLayerTree(this.target(), event.args["snapshot"]["active_tree"]["root_layer"], event.args["snapshot"]["device_viewport_size"]));
+            this.handleLayerTreeSnapshot(new WebInspector.DeferredTracingLayerTree(this.target().weakReference(), event.args["snapshot"]["active_tree"]["root_layer"], event.args["snapshot"]["device_viewport_size"]));
             return;
         }
         if (this._lastFrame && event.selfTime)
             this._lastFrame._addTimeForCategory(WebInspector.TracingTimelineUIUtils.eventStyle(event).category.name, event.selfTime);
 
         if (event.args["layerTreeId"] !== this._layerTreeId)
             return;
 
         var timestamp = event.startTime;
         if (event.name === eventNames.BeginFrame)
@@ skipping 164 matching lines @@
 /**
  * @constructor
  */
 WebInspector.PendingFrame = function()
 {
     /** @type {!Object.<string, number>} */
     this.timeByCategory = {};
     /** @type {!Array.<!WebInspector.LayerPaintEvent>} */
     this.paints = [];
 }