Video player: Reset the focus on entering fullscree mode.

ui/file_manager/video_player/js/media_controls.js

 // Copyright (c) 2012 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 MediaControls class implements media playback controls
  * that exist outside of the audio/video HTML element.
  */
 
 /**
@@ skipping 1075 matching lines @@
   if (fullscreen) {
     this.container_.setAttribute('fullscreen', '');
   } else {
     this.container_.removeAttribute('fullscreen');
   }
 
   if (this.fullscreenButton_) {
     this.fullscreenButton_.setAttribute('aria-label',
         fullscreen ? str('VIDEO_PLAYER_EXIT_FULL_SCREEN_BUTTON_LABEL')
                    : str('VIDEO_PLAYER_FULL_SCREEN_BUTTON_LABEL'));;
+    // If the fullscreen button has focus on entering fullscreen mode, reset the
+    // focus to make the spacebar toggle play/pause state. This is the
+    // consistent behavior with Youtube Web UI.
+    if (fullscreen)
+      this.fullscreenButton_.blur();
   }
 };