[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js

Index: third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js b/third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js
index 5a5736d4dea08dcd495de8d828667203a23539a6..68da74b384b73f6d3510855fc232f3e41a2e62f8 100644
--- a/third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js
+++ b/third_party/WebKit/Source/devtools/front_end/network/NetworkPanel.js
@@ -716,9 +716,10 @@ WebInspector.NetworkPanel.FilmStripRecorder.prototype = {
         if (!this._tracingModel)
             return;
         this._tracingModel.tracingComplete();
-        var resourceTreeModel = this._target.resourceTreeModel;
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this._target);
         this._target = null;
-        setImmediate(resourceTreeModel.resumeReload.bind(resourceTreeModel));
+        if (resourceTreeModel)
+            setImmediate(resourceTreeModel.resumeReload.bind(resourceTreeModel));
         this._callback(new WebInspector.FilmStripModel(this._tracingModel, this._timeCalculator.minimumBoundary() * 1000));
         delete this._callback;
     },
@@ -770,7 +771,9 @@ WebInspector.NetworkPanel.FilmStripRecorder.prototype = {
             return;
 
         this._target.tracingManager.stop();
-        this._target.resourceTreeModel.suspendReload();
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this._target);
+        if (resourceTreeModel)
+            resourceTreeModel.suspendReload();
         this._callback = callback;
         this._filmStripView.setStatusText(WebInspector.UIString("Fetching frames..."));
     }