[Media Router] Add UMA metrics to record the load time for route controls

chrome/test/data/webui/media_router/route_details_tests.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.
 
 /** @fileoverview Suite of tests for route-details. */
 cr.define('route_details', function() {
   function registerTests() {
     suite('RouteDetails', function() {
       /**
        * Route Details created before each test.
        * @type {RouteDetails}
        */
       var details;
 
       /**
        * First fake route created before each test.
        * @type {media_router.Route}
        */
       var fakeRouteOne;
 
       /**
+       * The custom controller path for |fakeRouteOne|.
+       * @const @type {string}
+       */
+      var fakeRouteOneControllerPath =
+          'chrome-extension://123/custom_view.html';
+
+      /**
        * Second fake route created before each test.
        * @type {media_router.Route}
        */
       var fakeRouteTwo;
 
       /**
        * Fake sink that corresponds to |fakeRouteOne|.
        * @type {media_router.Sink}
        */
       var fakeSinkOne;
@@ skipping 45 matching lines @@
       });
 
       // Initialize a route-details before each test.
       setup(function(done) {
         PolymerTest.clearBody();
         details = document.createElement('route-details');
         details.useWebUiRouteControls = false;
         document.body.appendChild(details);
 
         // Initialize routes and sinks.
-        fakeRouteOne = new media_router.Route('route id 1', 'sink id 1',
-            'Video 1', 1, true, false,
-            'chrome-extension://123/custom_view.html');
+        fakeRouteOne = new media_router.Route(
+            'route id 1', 'sink id 1', 'Video 1', 1, true, false,
+            fakeRouteOneControllerPath);
         fakeRouteTwo = new media_router.Route('route id 2', 'sink id 2',
             'Video 2', 2, false, true);
         fakeSinkOne = new media_router.Sink(
             'sink id 1', 'sink 1', 'description', null,
             media_router.SinkIconType.CAST, media_router.SinkStatus.ACTIVE,
             2 | 4);
 
         // Allow for the route details to be created and attached.
         setTimeout(done);
       });
@@ skipping 98 matching lines @@
             fakeRouteTwo.description), 'route-information');
         checkDefaultViewIsShown();
         checkStartCastButtonIsShown();
       });
 
       // Tests when |route| exists, has a custom controller, and it loads.
       test('route has custom controller and loading succeeds', function(done) {
         details.$$('extension-view-wrapper').$$('#custom-controller').load =
             function(url) {
           setTimeout(function() {
-            assertEquals('chrome-extension://123/custom_view.html', url);
+            assertEquals(
+                fakeRouteOneControllerPath,
+                url.substring(0, fakeRouteOneControllerPath.length));
             checkCustomControllerIsShown();
             done();
           });
           return Promise.resolve();
         };
 
         details.route = fakeRouteOne;
       });
 
       // Tests when |route| exists, has a custom controller, but fails to load.
       test('route has custom controller but loading fails', function(done) {
         details.$$('extension-view-wrapper').$$('#custom-controller').load =
             function(url) {
           setTimeout(function() {
             checkDefaultViewIsShown();
             done();
           });
           return Promise.reject();
         };
 
         details.route = fakeRouteOne;
       });
     });
   }
 
   return {
     registerTests: registerTests,
   };
 });