Leave fullscreen mode in an app window when ESC key is pressed.

chrome/test/data/extensions/platform_apps/leave_fullscreen/main.js

+// Copyright 2013 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.
+
+chrome.app.runtime.onLaunched.addListener(function() {
+  chrome.app.window.create('main.html', {}, function(win) {
+    chrome.test.sendMessage('Launched', function(reply) {
+      switch (reply) {
+        case 'window':
+          win.fullscreen();
+          break;
+        case 'dom':
+          win.contentWindow.document.addEventListener('keydown', function() {
+            win.contentWindow.document.removeEventListener('keydown',
+                                                           arguments.callee);
+            win.contentWindow.document.body.webkitRequestFullscreen();
+          });
+          break;
+      }
+    });
+  });
+});