[DevTools] Make resource tree model optional

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

Index: third_party/WebKit/Source/devtools/front_end/sdk/NetworkLog.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sdk/NetworkLog.js b/third_party/WebKit/Source/devtools/front_end/sdk/NetworkLog.js
index 35c086065c3696fc23a4abba0ea5c094af330a65..79e557df57054ff96bf3e042dfb9a0e74177bd38 100644
--- a/third_party/WebKit/Source/devtools/front_end/sdk/NetworkLog.js
+++ b/third_party/WebKit/Source/devtools/front_end/sdk/NetworkLog.js
@@ -33,17 +33,20 @@
  * @extends {WebInspector.SDKModel}
  * @param {!WebInspector.Target} target
  * @param {!WebInspector.NetworkManager} networkManager
+ * @param {?WebInspector.ResourceTreeModel} resourceTreeModel
  */
-WebInspector.NetworkLog = function(target, networkManager)
+WebInspector.NetworkLog = function(target, networkManager, resourceTreeModel)
 {
     WebInspector.SDKModel.call(this, WebInspector.NetworkLog, target);
 
     this._requests = [];
     this._requestForId = {};
     networkManager.addEventListener(WebInspector.NetworkManager.EventTypes.RequestStarted, this._onRequestStarted, this);
-    target.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._onMainFrameNavigated, this);
-    target.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.Load, this._onLoad, this);
-    target.resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.DOMContentLoaded, this._onDOMContentLoaded, this);
+    if (resourceTreeModel) {
+        resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._onMainFrameNavigated, this);
+        resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.Load, this._onLoad, this);
+        resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.DOMContentLoaded, this._onDOMContentLoaded, this);
+    }
 }
 
 /**