Timeline: fix screenshots for headless shell

third_party/WebKit/Source/devtools/front_end/components_lazy/FilmStripModel.js

 /*
  * Copyright 2015 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /**
  * @constructor
  * @param {!WebInspector.TracingModel} tracingModel
  * @param {number=} zeroTime
@@ skipping 15 matching lines @@
      * @param {!WebInspector.TracingModel} tracingModel
      * @param {number=} zeroTime
      */
     reset: function(tracingModel, zeroTime)
     {
         this._zeroTime = zeroTime || tracingModel.minimumRecordTime();
         this._spanTime = tracingModel.maximumRecordTime() - this._zeroTime;
 
         /** @type {!Array<!WebInspector.FilmStripModel.Frame>} */
         this._frames = [];
-
-        var browserProcess = tracingModel.processByName("Browser");
-        if (!browserProcess)
-            return;
-        var mainThread = browserProcess.threadByName("CrBrowserMain");
-        if (!mainThread)
+        var browserMain = WebInspector.TracingModel.browserMainThread(tracingModel);
+        if (!browserMain)
             return;
 
-        var events = mainThread.events();
+        var events = browserMain.events();
         for (var i = 0; i < events.length; ++i) {
             var event = events[i];
             if (event.startTime < this._zeroTime)
                 continue;
             if (!event.hasCategory(WebInspector.FilmStripModel._category))
                 continue;
             if (event.name === WebInspector.FilmStripModel.TraceEvents.CaptureFrame) {
                 var data = event.args["data"];
                 if (data)
                     this._frames.push(WebInspector.FilmStripModel.Frame._fromEvent(this, event, this._frames.length));
@@ skipping 94 matching lines @@
      * @return {!Promise<?string>}
      */
     imageDataPromise: function()
     {
         if (this._imageData || !this._snapshot)
             return Promise.resolve(this._imageData);
 
         return /** @type {!Promise<?string>} */ (this._snapshot.objectPromise());
     }
 }