[AppRemoting] Break out AppRemoting shared module (re-land).

remoting/webapp/app_remoting/js/ar_background.js

Index: remoting/webapp/app_remoting/js/ar_background.js
diff --git a/remoting/webapp/app_remoting/js/ar_background.js b/remoting/webapp/app_remoting/js/ar_background.js
index 4ee250768d2f5b94ed85a6213fa8b2ccb644cba0..d9ea8e51ddd57e44335837cd2ae143f8a21ff5d2 100644
--- a/remoting/webapp/app_remoting/js/ar_background.js
+++ b/remoting/webapp/app_remoting/js/ar_background.js
@@ -55,7 +55,10 @@ function createWindow(opt_launchData) {
     appWindow.onClosed.addListener(onClosed);
   };
 
-  chrome.app.window.create('main.html', windowAttributes, onCreate);
+  // TODO(garykac) Add code to switch between dev and prod shared modules.
+  chrome.app.window.create(
+      '_modules/koejkfhmphamcgafjmkellhnekdkopod/main.html',
+      windowAttributes, onCreate);
 };
 
 /** @param {Event} event */