Make |context| passed to queryRequiredElement optional

ui/file_manager/video_player/js/video_player.js

 // Copyright 2014 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.
 
 /**
  * @param {!HTMLElement} playerContainer Main container.
  * @param {!HTMLElement} videoContainer Container for the video element.
  * @param {!HTMLElement} controlsContainer Container for video controls.
  * @constructor
  * @struct
@@ skipping 96 matching lines @@
 FullWindowVideoControls.prototype.getInactivityWatcher = function() {
   return this.inactivityWatcher_;
 };
 
 /**
  * Displays error message.
  *
  * @param {string} message Message id.
  */
 FullWindowVideoControls.prototype.showErrorMessage = function(message) {
-  var errorBanner = queryRequiredElement(document, '#error');
+  var errorBanner = getRequiredElement('error');
   errorBanner.textContent = loadTimeData.getString(message);
   errorBanner.setAttribute('visible', 'true');
 
   // The window is hidden if the video has not loaded yet.
   chrome.app.window.current().show();
 };
 
 /**
  * Handles playback (decoder) errors.
  * @param {MediaError} error Error object.
  * @private
  */
 FullWindowVideoControls.prototype.onPlaybackError_ = function(error) {
   if (error.target && error.target.error &&
       error.target.error.code === MediaError.MEDIA_ERR_SRC_NOT_SUPPORTED) {
     if (this.casting)
       this.showErrorMessage('VIDEO_PLAYER_VIDEO_FILE_UNSUPPORTED_FOR_CAST');
     else
       this.showErrorMessage('VIDEO_PLAYER_VIDEO_FILE_UNSUPPORTED');
     this.decodeErrorOccured = false;
   } else {
     this.showErrorMessage('VIDEO_PLAYER_PLAYBACK_ERROR');
     this.decodeErrorOccured = true;
   }
 
   // Disable inactivity watcher, and disable the ui, by hiding tools manually.
   this.getInactivityWatcher().disabled = true;
-  queryRequiredElement(document, '#video-player')
-      .setAttribute('disabled', 'true');
+  getRequiredElement('video-player').setAttribute('disabled', 'true');
 
   // Detach the video element, since it may be unreliable and reset stored
   // current playback time.
   this.cleanup();
   this.clearState();
 
   // Avoid reusing a video element.
   player.unloadVideo();
 };
 
@@ skipping 55 matching lines @@
  * initialization.
  * @param {!Array<!FileEntry>} videos List of videos.
  */
 VideoPlayer.prototype.prepare = function(videos) {
   this.videos_ = videos;
 
   var preventDefault = function(event) { event.preventDefault(); }.wrap(null);
 
   document.ondragstart = preventDefault;
 
-  var maximizeButton = queryRequiredElement(document, '.maximize-button');
+  var maximizeButton = queryRequiredElement('.maximize-button');
   maximizeButton.addEventListener(
       'click',
       function(event) {
         var appWindow = chrome.app.window.current();
         if (appWindow.isMaximized())
           appWindow.restore();
         else
           appWindow.maximize();
         event.stopPropagation();
       }.wrap(null));
   maximizeButton.addEventListener('mousedown', preventDefault);
 
-  var minimizeButton = queryRequiredElement(document, '.minimize-button');
+  var minimizeButton = queryRequiredElement('.minimize-button');
   minimizeButton.addEventListener(
       'click',
       function(event) {
         chrome.app.window.current().minimize();
         event.stopPropagation();
       }.wrap(null));
   minimizeButton.addEventListener('mousedown', preventDefault);
 
-  var closeButton = queryRequiredElement(document, '.close-button');
+  var closeButton = queryRequiredElement('.close-button');
   closeButton.addEventListener(
       'click',
       function(event) {
         window.close();
         event.stopPropagation();
       }.wrap(null));
   closeButton.addEventListener('mousedown', preventDefault);
 
-  var menu = queryRequiredElement(document, '#cast-menu');
-  cr.ui.decorate(menu, cr.ui.Menu);
+  cr.ui.decorate(getRequiredElement('cast-menu'), cr.ui.Menu);
 
   this.controls_ = new FullWindowVideoControls(
-      queryRequiredElement(document, '#video-player'),
-      queryRequiredElement(document, '#video-container'),
-      queryRequiredElement(document, '#controls'));
+      getRequiredElement('video-player'),
+      getRequiredElement('video-container'),
+      getRequiredElement('controls'));
 
   var reloadVideo = function(e) {
     if (this.controls_.decodeErrorOccured &&
         // Ignore shortcut keys
         !e.ctrlKey && !e.altKey && !e.shiftKey && !e.metaKey) {
       this.reloadCurrentVideo(function() {
         this.videoElement_.play();
       }.wrap(this));
       e.preventDefault();
     }
   }.wrap(this);
 
-  var arrowRight = queryRequiredElement(document, '.arrow-box .arrow.right');
+  var arrowRight = queryRequiredElement('.arrow-box .arrow.right');
   arrowRight.addEventListener('click', this.advance_.wrap(this, 1));
-  var arrowLeft = queryRequiredElement(document, '.arrow-box .arrow.left');
+  var arrowLeft = queryRequiredElement('.arrow-box .arrow.left');
   arrowLeft.addEventListener('click', this.advance_.wrap(this, 0));
 
-  var videoPlayerElement = queryRequiredElement(document, '#video-player');
+  var videoPlayerElement = getRequiredElement('video-player');
   if (videos.length > 1)
     videoPlayerElement.setAttribute('multiple', true);
   else
     videoPlayerElement.removeAttribute('multiple');
 
   document.addEventListener('keydown', reloadVideo);
   document.addEventListener('click', reloadVideo);
 };
 
 /**
@@ skipping 15 matching lines @@
  * @param {!FileEntry} video Entry of the video to be played.
  * @param {function()=} opt_callback Completion callback.
  * @private
  */
 VideoPlayer.prototype.loadVideo_ = function(video, opt_callback) {
   this.unloadVideo(true);
 
   this.loadQueue_.run(function(callback) {
     document.title = video.name;
 
-    queryRequiredElement(document, '#title').innerText = video.name;
+    getRequiredElement('title').innerText = video.name;
 
-    var videoPlayerElement = queryRequiredElement(document, '#video-player');
+    var videoPlayerElement = getRequiredElement('video-player');
     if (this.currentPos_ === (this.videos_.length - 1))
       videoPlayerElement.setAttribute('last-video', true);
     else
       videoPlayerElement.removeAttribute('last-video');
 
     if (this.currentPos_ === 0)
       videoPlayerElement.setAttribute('first-video', true);
     else
       videoPlayerElement.removeAttribute('first-video');
 
     // Re-enables ui and hides error message if already displayed.
-    queryRequiredElement(document, '#video-player').removeAttribute('disabled');
-    queryRequiredElement(document, '#error').removeAttribute('visible');
+    getRequiredElement('video-player').removeAttribute('disabled');
+    getRequiredElement('error').removeAttribute('visible');
     this.controls.detachMedia();
     this.controls.getInactivityWatcher().disabled = true;
     this.controls.decodeErrorOccured = false;
     this.controls.casting = !!this.currentCast_;
 
     videoPlayerElement.setAttribute('loading', true);
 
     var media = new MediaManager(video);
 
     Promise.all([media.getThumbnail(), media.getToken(false)])
         .then(function(results) {
           var url = results[0];
           var token = results[1];
           if (url && token) {
-            queryRequiredElement(document, '#thumbnail').style.backgroundImage =
+            getRequiredElement('thumbnail').style.backgroundImage =
                 'url(' + url + '&access_token=' + token + ')';
           } else {
-            queryRequiredElement(document, '#thumbnail').style.backgroundImage =
-                '';
+            getRequiredElement('thumbnail').style.backgroundImage = '';
           }
         })
         .catch(function() {
           // Shows no image on error.
-          queryRequiredElement(document, '#thumbnail').style.backgroundImage =
-              '';
+          getRequiredElement('thumbnail').style.backgroundImage = '';
         });
 
     var videoElementInitializePromise;
     if (this.currentCast_) {
       metrics.recordPlayType(metrics.PLAY_TYPE.CAST);
 
       videoPlayerElement.setAttribute('casting', true);
 
-      queryRequiredElement(document, '#cast-name').textContent =
+      getRequiredElement('cast-name').textContent =
           this.currentCast_.friendlyName;
 
       videoPlayerElement.setAttribute('castable', true);
 
       videoElementInitializePromise = media.isAvailableForCast()
           .then(function(result) {
             if (!result)
               return Promise.reject('No casts are available.');
 
             return new Promise(function(fulfill, reject) {
               chrome.cast.requestSession(
                   fulfill, reject, undefined, this.currentCast_.label);
             }.bind(this)).then(function(session) {
               session.addUpdateListener(this.onCastSessionUpdateBound_);
 
               this.currentSession_ = session;
               this.videoElement_ = new CastVideoElement(media, session);
               this.controls.attachMedia(this.videoElement_);
             }.bind(this));
           }.bind(this));
     } else {
       metrics.recordPlayType(metrics.PLAY_TYPE.LOCAL);
       videoPlayerElement.removeAttribute('casting');
 
       this.videoElement_ = document.createElement('video');
-      queryRequiredElement(document, '#video-container').appendChild(
-          this.videoElement_);
+      getRequiredElement('video-container').appendChild(this.videoElement_);
 
       this.controls.attachMedia(this.videoElement_);
       this.videoElement_.src = video.toURL();
 
       media.isAvailableForCast().then(function(result) {
         if (result)
           videoPlayerElement.setAttribute('castable', true);
         else
           videoPlayerElement.removeAttribute('castable');
       }).catch(function() {
@@ skipping 171 matching lines @@
     this.reloadCurrentVideo();
     callback();
   }.wrap(this));
 };
 
 /**
  * Set the list of casts.
  * @param {Array<Object>} casts List of casts.
  */
 VideoPlayer.prototype.setCastList = function(casts) {
-  var videoPlayerElement = queryRequiredElement(document, '#video-player');
-  var menu = queryRequiredElement(document, '#cast-menu');
+  var videoPlayerElement = getRequiredElement('video-player');
+  var menu = getRequiredElement('cast-menu');
   menu.innerHTML = '';
 
   // TODO(yoshiki): Handle the case that the current cast disappears.
 
   if (casts.length === 0) {
     videoPlayerElement.removeAttribute('cast-available');
     if (this.currentCast_)
       this.onCurrentCastDisappear_();
     return;
   }
@@ skipping 25 matching lines @@
   }
   this.updateCheckOnCastMenu_();
   videoPlayerElement.setAttribute('cast-available', true);
 };
 
 /**
  * Updates the check status of the cast menu items.
  * @private
  */
 VideoPlayer.prototype.updateCheckOnCastMenu_ = function() {
-  var menu = queryRequiredElement(document, '#cast-menu');
-  var menuItems = menu.menuItems;
+  var menuItems = getRequiredElement('cast-menu').menuItems;
   for (var i = 0; i < menuItems.length; i++) {
     var item = menuItems[i];
     if (this.currentCast_ === null) {
       // Playing on this computer.
       if (item.castLabel === '')
         item.checked = true;
       else
         item.checked = false;
     } else {
       // Playing on cast device.
@@ skipping 58 matching lines @@
   return new Promise(function(fulfill, reject) {
     util.URLsToEntries(window.appState.items, function(entries) {
       metrics.recordOpenVideoPlayerAction();
       metrics.recordNumberOfOpenedFiles(entries.length);
 
       player.prepare(entries);
       player.playFirstVideo(player, fulfill);
     }.wrap());
   }.wrap());
 }.wrap());