DevTools: Get rid of WebInspector.TargetObserver

Source/devtools/front_end/profiler/ProfilesPanel.js

 /*
  * Copyright (C) 2008 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 286 matching lines @@
 
 /**
  * @constructor
  * @extends {WebInspector.Object}
  * @param {?WebInspector.Target} target
  * @param {!WebInspector.ProfileType} profileType
  * @param {string} title
  */
 WebInspector.ProfileHeader = function(target, profileType, title)
 {
-    this._targetObserver = new WebInspector.TargetObserver(target);
+    this._weakTarget = target ? target.weakReference() : new WeakReference(null);
     this._profileType = profileType;
     this.title = title;
     this.uid = profileType._nextProfileUid++;
     this._fromFile = false;
 }
 
 /**
  * @constructor
  * @param {?string} subtitle
  * @param {boolean|undefined} wait
@@ skipping 10 matching lines @@
     UpdateStatus: "UpdateStatus",
     ProfileReceived: "ProfileReceived"
 }
 
 WebInspector.ProfileHeader.prototype = {
     /**
      * @return {?WebInspector.Target}
      */
     target: function()
     {
-        return this._targetObserver.target();
+        return this._weakTarget.get();
     },
 
     /**
+     * @return {!WeakReference.<!WebInspector.Target>}
+     */
+    weakTarget: function()
+    {
+        return this._weakTarget;
+    },
+
+    /**
      * @return {!WebInspector.ProfileType}
      */
     profileType: function()
     {
         return this._profileType;
     },
 
     /**
      * @param {?string} subtitle
      * @param {boolean=} wait
@@ skipping 1003 matching lines @@
 importScript("HeapSnapshotCommon.js");
 importScript("HeapSnapshotProxy.js");
 importScript("HeapSnapshotDataGrids.js");
 importScript("HeapSnapshotGridNodes.js");
 importScript("HeapSnapshotView.js");
 importScript("ProfileLauncherView.js");
 importScript("CanvasProfileView.js");
 importScript("CanvasReplayStateView.js");
 
 WebInspector.ProfileTypeRegistry.instance = new WebInspector.ProfileTypeRegistry();