Enable all ESC-Fullscreen tests (Chrome Apps) for all platforms.

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) {
     // The following key events handler should have no effect because the
     // application does not have the 'overrideEscFullscreen' permission.
     win.contentWindow.document.addEventListener('keydown', function(e) {
       e.preventDefault();
     });
     win.contentWindow.document.addEventListener('keyup', function(e) {
       e.preventDefault();
     });
 
     chrome.test.sendMessage('Launched', function(reply) {
+      win.contentWindow.document.addEventListener('keydown', function(e) {
+        if (e.keyCode != 90) // 'z'
+          return;
+
+        chrome.test.sendMessage('KeyReceived');
+      });
+
       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;
       }
     });
   });
 });