[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/sdk/CSSModel.js

 /*
  * Copyright (C) 2010 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 21 matching lines @@
  * @constructor
  * @extends {WebInspector.SDKModel}
  * @param {!WebInspector.Target} target
  */
 WebInspector.CSSModel = function(target)
 {
     WebInspector.SDKModel.call(this, WebInspector.CSSModel, target);
     this._domModel = WebInspector.DOMModel.fromTarget(target);
     this._agent = target.cssAgent();
     this._styleLoader = new WebInspector.CSSModel.ComputedStyleLoader(this);
-    target.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._mainFrameNavigated, this);
+    var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(target);
+    if (resourceTreeModel)
+        resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._mainFrameNavigated, this);
     target.registerCSSDispatcher(new WebInspector.CSSDispatcher(this));
     this._agent.enable().then(this._wasEnabled.bind(this));
     /** @type {!Map.<string, !WebInspector.CSSStyleSheetHeader>} */
     this._styleSheetIdToHeader = new Map();
     /** @type {!Map.<string, !Object.<!PageAgent.FrameId, !Array.<!CSSAgent.StyleSheetId>>>} */
     this._styleSheetIdsForURL = new Map();
 
     /** @type {!Map.<!WebInspector.CSSStyleSheetHeader, !Promise<string>>} */
     this._originalStyleSheetText = new Map();
 
@@ skipping 667 matching lines @@
             return new WebInspector.CSSStyleRule(this, rulePayload);
         }
     },
 
     /**
      * @param {!WebInspector.DOMNode} node
      * @param {function(?WebInspector.CSSStyleSheetHeader)} userCallback
      */
     requestViaInspectorStylesheet: function(node, userCallback)
     {
-        var frameId = node.frameId() || this.target().resourceTreeModel.mainFrame.id;
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this.target());
+        var frameId = node.frameId() || (resourceTreeModel && resourceTreeModel.mainFrame.id);
         var headers = this._styleSheetIdToHeader.valuesArray();
         for (var i = 0; i < headers.length; ++i) {
             var styleSheetHeader = headers[i];
             if (styleSheetHeader.frameId === frameId && styleSheetHeader.isViaInspector()) {
                 userCallback(styleSheetHeader);
                 return;
             }
         }
 
         /**
@@ skipping 461 matching lines @@
 /**
  * @constructor
  * @param {?WebInspector.CSSStyleDeclaration} inlineStyle
  * @param {?WebInspector.CSSStyleDeclaration} attributesStyle
  */
 WebInspector.CSSModel.InlineStyleResult = function(inlineStyle, attributesStyle)
 {
     this.inlineStyle = inlineStyle;
     this.attributesStyle = attributesStyle;
 }