Timeline: check category presence in list, not string equality

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
  */
 WebInspector.FilmStripModel = function(tracingModel)
 {
     this._tracingModel = tracingModel;
 
     /** @type {!Array<!WebInspector.FilmStripModel.Frame>} */
     this._frames = [];
 
     var browserProcess = tracingModel.processByName("Browser");
     if (!browserProcess)
         return;
     var mainThread = browserProcess.threadByName("CrBrowserMain");
     if (!mainThread)
         return;
 
     var events = mainThread.events();
     for (var i = 0; i < events.length; ++i) {
-        if (events[i].category !== "disabled-by-default-devtools.screenshot")
+        if (!events[i].hasCategory(WebInspector.FilmStripModel._category))
             continue;
 
         if (events[i].name === WebInspector.FilmStripModel.TraceEvents.CaptureFrame) {
             var data = events[i].args["data"];
             if (data)
                 this._frames.push(WebInspector.FilmStripModel.Frame._fromEvent(this, events[i], this._frames.length));
         } else if (events[i].name === WebInspector.FilmStripModel.TraceEvents.Screenshot) {
             this._frames.push(WebInspector.FilmStripModel.Frame._fromSnapshot(this, /** @type {!WebInspector.TracingModel.ObjectSnapshot} */ (events[i]), this._frames.length));
         }
     }
 }
 
+WebInspector.FilmStripModel._category = "disabled-by-default-devtools.screenshot";
+
 WebInspector.FilmStripModel.TraceEvents = {
     CaptureFrame: "CaptureFrame",
     Screenshot: "Screenshot"
 }
 
 WebInspector.FilmStripModel.prototype = {
     /**
      * @return {!Array<!WebInspector.FilmStripModel.Frame>}
      */
     frames: function()
@@ skipping 85 matching lines @@
      * @return {!Promise<?string>}
      */
     imageDataPromise: function()
     {
         if (this._imageData || !this._snapshot)
             return Promise.resolve(this._imageData);
 
         return /** @type {!Promise<?string>} */ (this._snapshot.objectPromise());
     }
 }