Make |context| passed to queryRequiredElement optional

ui/file_manager/gallery/js/gallery.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.
 
 /**
  * Overrided metadata worker's path.
  * @type {string}
  */
 ContentMetadataProvider.WORKER_SCRIPT = '/js/metadata_worker.js';
 
 /**
  * Gallery for viewing and editing image files.
  *
  * @param {!VolumeManagerWrapper} volumeManager
  * @constructor
  * @struct
  */
 function Gallery(volumeManager) {
   /**
    * @type {{appWindow: chrome.app.window.AppWindow, readonlyDirName: string,
    *     displayStringFunction: function(), loadTimeData: Object}}
    * @private
    */
   this.context_ = {
     appWindow: chrome.app.window.current(),
     readonlyDirName: '',
     displayStringFunction: function() { return ''; },
     loadTimeData: {},
   };
-  this.container_ = queryRequiredElement(document, '.gallery');
+  this.container_ = queryRequiredElement('.gallery');
   this.document_ = document;
   this.volumeManager_ = volumeManager;
   /**
    * @private {!MetadataModel}
    * @const
    */
   this.metadataModel_ = MetadataModel.create(volumeManager);
   /**
    * @private {!ThumbnailModel}
    * @const
@@ skipping 26 matching lines @@
    */
   this.changingMode_ = false;
 
   // -----------------------------------------------------------------
   // Initializes the UI.
 
   // Initialize the dialog label.
   cr.ui.dialogs.BaseDialog.OK_LABEL = str('GALLERY_OK_LABEL');
   cr.ui.dialogs.BaseDialog.CANCEL_LABEL = str('GALLERY_CANCEL_LABEL');
 
-  var content = queryRequiredElement(document, '#content');
+  var content = getRequiredElement('content');
   content.addEventListener('click', this.onContentClick_.bind(this));
 
-  this.topToolbar_ = queryRequiredElement(document, '#top-toolbar');
-  this.bottomToolbar_ = queryRequiredElement(document, '#bottom-toolbar');
+  this.topToolbar_ = getRequiredElement('top-toolbar');
+  this.bottomToolbar_ = getRequiredElement('bottom-toolbar');
 
-  this.filenameSpacer_ = queryRequiredElement(this.topToolbar_,
-      '.filename-spacer');
+  this.filenameSpacer_ = queryRequiredElement('.filename-spacer',
+      this.topToolbar_);
 
   /**
    * @private {HTMLInputElement}
    * @const
    */
   this.filenameEdit_ = /** @type {HTMLInputElement} */
-      (queryRequiredElement(this.filenameSpacer_, 'input'));
+      (queryRequiredElement('input', this.filenameSpacer_));
 
   this.filenameCanvas_ = document.createElement('canvas');
   this.filenameCanvasContext_ = this.filenameCanvas_.getContext('2d');
 
   // Set font style of canvas context to same font style with rename field.
   var filenameEditComputedStyle = window.getComputedStyle(this.filenameEdit_);
   this.filenameCanvasContext_.font = filenameEditComputedStyle.font;
 
   this.filenameEdit_.addEventListener('blur',
       this.onFilenameEditBlur_.bind(this));
   this.filenameEdit_.addEventListener('focus',
       this.onFilenameFocus_.bind(this));
   this.filenameEdit_.addEventListener('input',
       this.resizeRenameField_.bind(this));
   this.filenameEdit_.addEventListener('keydown',
       this.onFilenameEditKeydown_.bind(this));
 
-  var buttonSpacer = queryRequiredElement(this.topToolbar_, '.button-spacer');
+  var buttonSpacer = queryRequiredElement('.button-spacer', this.topToolbar_);
 
   this.prompt_ = new ImageEditor.Prompt(this.container_, strf);
 
   this.errorBanner_ = new ErrorBanner(this.container_);
 
   /**
    * @private {!HTMLElement}
    * @const
    */
-  this.modeSwitchButton_ = queryRequiredElement(this.topToolbar_,
-      'button.mode');
+  this.modeSwitchButton_ = queryRequiredElement('button.mode',
+      this.topToolbar_);
   GalleryUtil.decorateMouseFocusHandling(this.modeSwitchButton_);
   this.modeSwitchButton_.addEventListener('click',
       this.onModeSwitchButtonClicked_.bind(this));
 
   /**
    * @private {!PaperRipple}
    */
   this.modeSwitchButtonRipple_ = /** @type {!PaperRipple} */
-      (queryRequiredElement(this.modeSwitchButton_, 'paper-ripple'));
+      (queryRequiredElement('paper-ripple', this.modeSwitchButton_));
 
   /**
    * @private {!DimmableUIController}
    * @const
    */
   this.dimmableUIController_ = new DimmableUIController(this.container_);
 
   this.thumbnailMode_ = new ThumbnailMode(
       assertInstanceof(document.querySelector('.thumbnail-view'), HTMLElement),
       this.errorBanner_,
@@ skipping 19 matching lines @@
                                   this.dimmableUIController_);
   this.slideMode_.addEventListener('image-displayed', function() {
     cr.dispatchSimpleEvent(this, 'image-displayed');
   }.bind(this));
 
   /**
    * @private {!HTMLElement}
    * @const
    */
   this.deleteButton_ = queryRequiredElement(
-      this.topToolbar_, 'paper-button.delete');
+      'paper-button.delete', this.topToolbar_);
   this.deleteButton_.addEventListener('click', this.delete_.bind(this));
 
   /**
    * @private {!HTMLElement}
    * @const
    */
-  this.slideshowButton_ = queryRequiredElement(this.topToolbar_,
-      'paper-button.slideshow');
+  this.slideshowButton_ = queryRequiredElement('paper-button.slideshow',
+      this.topToolbar_);
 
   /**
    * @private {!HTMLElement}
    * @const
    */
   this.shareButton_ = queryRequiredElement(
-      this.topToolbar_, 'paper-button.share');
+      'paper-button.share', this.topToolbar_);
   this.shareButton_.addEventListener(
       'click', this.onShareButtonClick_.bind(this));
 
   this.dataModel_.addEventListener('splice', this.onSplice_.bind(this));
   this.dataModel_.addEventListener('content', this.onContentChange_.bind(this));
 
   this.selectionModel_.addEventListener('change', this.onSelection_.bind(this));
   this.slideMode_.addEventListener('useraction', this.onUserAction_.bind(this));
 
   this.shareDialog_ = new ShareDialog(this.container_);
@@ skipping 774 matching lines @@
  */
 var initializePromise =
     Promise.all([loadTimeDataPromise, volumeManagerPromise]).
     then(function(args) {
       var volumeManager = args[1];
       gallery = new Gallery(volumeManager);
     });
 
 // Loads entries.
 initializePromise.then(reload);