DevTools: support importing layer tree from trace snapshots.

Source/devtools/front_end/LayersPanel.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 83 matching lines @@
     },
 
     /**
      * @param {!WebInspector.LayerTreeSnapshot} snapshot
      */
     _showSnapshot: function(snapshot)
     {
         this._model.setSnapshot(snapshot);
     },
 
+    /**
+     * @param {!WebInspector.TracingLayerSnapshot} snapshot
+     */
+    _showTracingSnapshot: function(snapshot)
+    {
+        this._model.setTracingSnapshot(snapshot);
+    },
+
     _onLayerTreeUpdated: function()
     {
         if (this._currentlySelectedLayer && !this._model.layerById(this._currentlySelectedLayer.id()))
             this._selectLayer(null);
         if (this._currentlyHoveredLayer && !this._model.layerById(this._currentlyHoveredLayer.id()))
             this._hoverLayer(null);
     },
 
     /**
      * @param {!WebInspector.Event} event
@@ skipping 64 matching lines @@
 /**
  * @constructor
  * @implements {WebInspector.Revealer}
  */
 WebInspector.LayersPanel.LayerTreeRevealer = function()
 {
 }
 
 WebInspector.LayersPanel.LayerTreeRevealer.prototype = {
     /**
-     * @param {!Object} layerTree
+     * @param {!Object} snapshotData
      */
-    reveal: function(layerTree)
+    reveal: function(snapshotData)
     {
-        if (layerTree instanceof WebInspector.LayerTreeSnapshot)
-            /** @type {!WebInspector.LayersPanel} */ (WebInspector.inspectorView.showPanel("layers"))._showSnapshot(layerTree);
+        if (snapshotData instanceof WebInspector.LayerTreeSnapshot)
+            /** @type {!WebInspector.LayersPanel} */ (WebInspector.inspectorView.showPanel("layers"))._showSnapshot(snapshotData);
+        else if (snapshotData instanceof WebInspector.TracingLayerSnapshot)
+            /** @type {!WebInspector.LayersPanel} */ (WebInspector.inspectorView.showPanel("layers"))._showTracingSnapshot(snapshotData);
     }
 }