[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js

 /*
  * Copyright (C) 2012 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 26 matching lines @@
  */
 WebInspector.StylesSourceMapping = function(cssModel, workspace, networkMapping)
 {
     this._cssModel = cssModel;
     this._workspace = workspace;
     this._workspace.addEventListener(WebInspector.Workspace.Events.ProjectRemoved, this._projectRemoved, this);
     this._workspace.addEventListener(WebInspector.Workspace.Events.UISourceCodeAdded, this._uiSourceCodeAddedToWorkspace, this);
     this._workspace.addEventListener(WebInspector.Workspace.Events.UISourceCodeRemoved, this._uiSourceCodeRemoved, this);
     this._networkMapping = networkMapping;
 
-    cssModel.target().resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._unbindAllUISourceCodes, this);
+    var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(cssModel.target());
+    if (resourceTreeModel)

[pfeldman, 2016/07/07 17:44:14]

We always have resourceTreeModel when we have CSS.

[eostroukhov-old, 2016/07/13 23:30:58]

I added an accessor to get it through the cssModel.

+        resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._unbindAllUISourceCodes, this);
 
     this._cssModel.addEventListener(WebInspector.CSSModel.Events.StyleSheetChanged, this._styleSheetChanged, this);
     /** @type {!Map<string, !Map<string, !Map<string, !WebInspector.CSSStyleSheetHeader>>>} */
     this._urlToHeadersByFrameId = new Map();
     /** @type {!Map.<!WebInspector.UISourceCode, !WebInspector.StyleFile>} */
     this._styleFiles = new Map();
 }
 
 WebInspector.StylesSourceMapping.ChangeUpdateTimeoutMs = 200;
 
@@ skipping 338 matching lines @@
     },
 
     dispose: function()
     {
         if (this._terminated)
             return;
         this._terminated = true;
         WebInspector.EventTarget.removeEventListeners(this._eventListeners);
     }
 }