[DevTools] Remove dependency from TargetManager to ResourceTreeModel

third_party/WebKit/Source/devtools/front_end/layers/LayerTreeModel.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 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 /**
  * @unrestricted
  */
 Layers.LayerTreeModel = class extends SDK.SDKModel {
   constructor(target) {
     super(target);
     target.registerLayerTreeDispatcher(new Layers.LayerTreeDispatcher(this));
-    SDK.targetManager.addEventListener(SDK.TargetManager.Events.MainFrameNavigated, this._onMainFrameNavigated, this);
+    var resourceTreeModel = target.model(SDK.ResourceTreeModel);
+    if (resourceTreeModel) {
+      resourceTreeModel.addEventListener(
+          SDK.ResourceTreeModel.Events.MainFrameNavigated, this._onMainFrameNavigated, this);
+    }
     /** @type {?SDK.LayerTreeBase} */
     this._layerTree = null;
   }
 
   /**
    * @param {!SDK.Target} target
    * @return {?Layers.LayerTreeModel}
    */
   static fromTarget(target) {
     return target.model(Layers.LayerTreeModel);
@@ skipping 507 matching lines @@
 
   /**
    * @override
    * @param {!Protocol.LayerTree.LayerId} layerId
    * @param {!Protocol.DOM.Rect} clipRect
    */
   layerPainted(layerId, clipRect) {
     this._layerTreeModel._layerPainted(layerId, clipRect);
   }
 };