Explicit initialization of aura::Env for browser shell.

ui/aura/env.h

 // 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.
 
 #ifndef UI_AURA_ENV_H_
 #define UI_AURA_ENV_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/observer_list.h"
@@ skipping 16 matching lines @@
 base::MessageLoop::Dispatcher* CreateDispatcher();
 #endif
 
 // A singleton object that tracks general state within Aura.
 // TODO(beng): manage RootWindows.
 class AURA_EXPORT Env : public ui::EventTarget {
  public:
   Env();
   virtual ~Env();
 
+  static void CreateInstance();
   static Env* GetInstance();
   static void DeleteInstance();
 
   void AddObserver(EnvObserver* observer);
   void RemoveObserver(EnvObserver* observer);
 
   bool is_mouse_button_down() const { return mouse_button_flags_ != 0; }
   void set_mouse_button_flags(int mouse_button_flags) {
     mouse_button_flags_ = mouse_button_flags;
   }
@@ skipping 50 matching lines @@
 #if defined(USE_X11)
   DeviceListUpdaterAuraX11 device_list_updater_aurax11_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_