Make app_custom_bindings.js lazily evaluated so it doesn't execute on every page load.

chrome/renderer/resources/extensions/app_custom_bindings.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.
 
 // Custom bindings for the app API.
 
 var appNatives = requireNative('app');
-var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
-chrome.app = {
+// This becomes chrome.app
+var app = {
   getIsInstalled: appNatives.GetIsInstalled,
   install: appNatives.Install,
   getDetails: appNatives.GetDetails,
   getDetailsForFrame: appNatives.GetDetailsForFrame
 };
 
 // Tricky; "getIsInstalled" is actually exposed as the getter "isInstalled",
 // but we don't have a way to express this in the schema JSON (nor is it
 // worth it for this one special case).
 //
 // So, define it manually, and let the getIsInstalled function act as its
 // documentation.
-chrome.app.__defineGetter__('isInstalled', appNatives.GetIsInstalled);
+app.__defineGetter__('isInstalled', appNatives.GetIsInstalled);
 
 // Called by app_bindings.cc.
-chromeHidden.app = {
+// This becomes chromeHidden.app
+var chromeHiddenApp = {
   onGetAppNotifyChannelResponse: function(channelId, error, callbackId) {
     if (callbackId) {
       callbacks[callbackId](channelId, error);
       delete callbacks[callbackId];
     }
   }
 };
 
 // appNotification stuff.
 //
 // TODO(kalman): move this stuff to its own custom bindings.
 // It will be bit tricky since I'll need to look into why there are
 // permissions defined for app notifications, yet this always sets it up?
 var callbacks = {};
 var nextCallbackId = 1;
 
-chrome.appNotifications = {
+// This becomes chrome.appNotifications.
+var appNotifications = {
   getChannel: function getChannel(clientId, callback) {
     var callbackId = 0;
     if (callback) {
       callbackId = nextCallbackId++;
       callbacks[callbackId] = callback;
     }
     appNatives.GetAppNotifyChannel(clientId, callbackId);
   }
 };
+
+// These must match the names in InstallAppBindings() in
+// extension_dispatcher.cc.
+exports.chromeApp = app;
+exports.chromeAppNotifications = appNotifications;
+exports.chromeHiddenApp = chromeHiddenApp;