Escape key should exit the fullscreen mode when playing a video.

chrome/browser/resources/file_manager/js/media/video_player.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.
 
 /**
  * Display error message.
  * @param {string} message Message id.
  */
 function showErrorMessage(message) {
   var errorBanner = document.querySelector('#error');
@@ skipping 40 matching lines @@
       onPlaybackError,
       function() { chrome.fileBrowserPrivate.toggleFullscreen() },
       videoContainer);
 
   this.playerContainer_ = playerContainer;
 
   this.updateStyle();
   window.addEventListener('resize', this.updateStyle.bind(this));
 
   document.addEventListener('keydown', function(e) {
-    if (e.keyIdentifier == 'U+0020') {
+    if (e.keyIdentifier == 'U+0020') {  // Space
       this.togglePlayStateWithFeedback();
       e.preventDefault();
     }
+    if (e.keyIdentifier == 'U+001B') {  // Escape
+      chrome.fileBrowserPrivate.isFullscreen(function(enabled) {
+        if (enabled)
+          chrome.fileBrowserPrivate.toggleFullscreen();
+      });
+      e.preventDefault();
+    }
   }.bind(this));
 
   util.disableBrowserShortcutKeys(document);
 
   videoContainer.addEventListener('click',
       this.togglePlayStateWithFeedback.bind(this));
 
   this.inactivityWatcher_ = new MouseInactivityWatcher(playerContainer);
   this.__defineGetter__('inactivityWatcher', function() {
     return this.inactivityWatcher_;
@@ skipping 180 matching lines @@
     webkitResolveLocalFileSystemURL(src,
       function(entry) {
         var video = document.querySelector('video');
         if (video.src != src) return;
         selectedItemFilesystemPath = entry.fullPath;
       });
   });
 }
 
 util.addPageLoadHandler(loadVideoPlayer);