Gallery: Add support for Media Keys

ui/file_manager/gallery/js/slide_mode.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.
 
 'use strict';
 
 /**
  * Slide mode displays a single image and has a set of controls to navigate
  * between the images and to edit an image.
  *
@@ skipping 589 matching lines @@
   } else {
     return advance(this.getSelectedIndex(), this.getItemCount_());
   }
 };
 
 /**
  * Advance the selection based on the pressed key ID.
  * @param {string} keyID Key identifier.
  */
 SlideMode.prototype.advanceWithKeyboard = function(keyID) {
-  this.advanceManually(keyID === 'Up' || keyID === 'Left' ? -1 : 1);
+  var prev = (keyID === 'Up' ||
+              keyID === 'Left' ||
+              keyID === 'MediaPreviousTrack');
+  this.advanceManually(prev ? -1 : 1);
 };
 
 /**
  * Advance the selection as a result of a user action (as opposed to an
  * automatic change in the slideshow mode).
  * @param {number} direction -1 for left, 1 for right.
  */
 SlideMode.prototype.advanceManually = function(direction) {
   if (this.isSlideshowPlaying_())
     this.pauseSlideshow_();
@@ skipping 178 matching lines @@
  *
  * @param {Event} event Event.
  * @return {boolean} True if handled.
  */
 SlideMode.prototype.onKeyDown = function(event) {
   var keyID = util.getKeyModifiers(event) + event.keyIdentifier;
 
   if (this.isSlideshowOn_()) {
     switch (keyID) {
       case 'U+001B':  // Escape exits the slideshow.
+      case 'MediaStop':
         this.stopSlideshow_(event);
         break;
 
       case 'U+0020':  // Space pauses/resumes the slideshow.
+      case 'MediaPlayPause':
         this.toggleSlideshowPause_();
         break;
 
       case 'Up':
       case 'Down':
       case 'Left':
       case 'Right':
+      case 'MediaNextTrack':
+      case 'MediaPreviousTrack':
         this.advanceWithKeyboard(keyID);
         break;
     }
     return true;  // Consume all keystrokes in the slideshow mode.
   }
 
   if (this.isEditing() && this.editor_.onKeyDown(event))
     return true;
 
   switch (keyID) {
@@ skipping 16 matching lines @@
     case 'Home':
       this.selectFirst();
       break;
     case 'End':
       this.selectLast();
       break;
     case 'Up':
     case 'Down':
     case 'Left':
     case 'Right':
+    case 'MediaNextTrack':
+    case 'MediaPreviousTrack':
       this.advanceWithKeyboard(keyID);
       break;
 
     default: return false;
   }
 
   return true;
 };
 
 /**
@@ skipping 397 matching lines @@
       done = true;
     }
   }.bind(this);
 };
 
 /**
  * If the user touched the image and moved the finger more than SWIPE_THRESHOLD
  * horizontally it's considered as a swipe gesture (change the current image).
  */
 SwipeOverlay.SWIPE_THRESHOLD = 100;