Removes the dependency to WMTestHelper from app shell.

apps/shell/browser/shell_browser_main_delegate.h

 // Copyright 2014 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.
 
 #ifndef APPS_SHELL_BROWSER_SHELL_BROWSER_MAIN_DELEGATE_H_
 #define APPS_SHELL_BROWSER_SHELL_BROWSER_MAIN_DELEGATE_H_
 
 namespace content {
 class BrowserContext;
 }
 
 namespace apps {
 
+class ShellDesktopController;
+
 class ShellBrowserMainDelegate {
  public:
   virtual ~ShellBrowserMainDelegate() {}
 
   // Called to start an application after all initialization processes that are
   // necesary to run apps are completed.
   virtual void Start(content::BrowserContext* context) = 0;
 
   // Called after the main message looop has stopped, but before
   // other services such as BrowserContext / extension system are shut down.
   virtual void Shutdown() = 0;
+
+  // Creates the ShellDesktopController instance to initialize the root window
+  // and window manager. Subclass may return its subclass to customize the
+  // windo wmanager.
+  virtual ShellDesktopController* CreateDesktopController() = 0;
 };
 
 }  // namespace apps
 
 #endif  // APPS_SHELL_BROWSER_SHELL_BROWSER_MAIN_DELEGATE_H_