Use a mocked compositor for unit tests

ui/aura/desktop.h

 // Copyright (c) 2011 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_DESKTOP_H_
 #define UI_AURA_DESKTOP_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
@@ skipping 31 matching lines @@
 class AURA_EXPORT Desktop : public ui::CompositorDelegate,
                             public Window,
                             public internal::FocusManager {
  public:
   Desktop();
   virtual ~Desktop();
 
   static Desktop* GetInstance();
   static void DeleteInstanceForTesting();
 
-  static void set_compositor_factory_for_testing(ui::Compositor*(*factory)()) {
-    compositor_factory_ = factory;
-  }
-  static ui::Compositor* (*compositor_factory())() {
-    return compositor_factory_;
-  }
-
   ui::Compositor* compositor() { return compositor_.get(); }
   gfx::Point last_mouse_location() const { return last_mouse_location_; }
   DesktopDelegate* delegate() { return delegate_.get(); }
   Window* active_window() { return active_window_; }
   Window* mouse_pressed_handler() { return mouse_pressed_handler_; }
   Window* capture_window() { return capture_window_; }
   ScreenAura* screen() { return screen_; }
 
   void SetDelegate(DesktopDelegate* delegate);
 
@@ skipping 94 matching lines @@
 
   scoped_ptr<DesktopHost> host_;
 
   scoped_ptr<DesktopDelegate> delegate_;
 
   static Desktop* instance_;
 
   // Used to schedule painting.
   base::WeakPtrFactory<Desktop> schedule_paint_factory_;
 
-  // Factory used to create Compositors. Settable by tests.
-  static ui::Compositor*(*compositor_factory_)();
-
   Window* active_window_;
 
   // Last location seen in a mouse event.
   gfx::Point last_mouse_location_;
 
   // Are we in the process of being destroyed? Used to avoid processing during
   // destruction.
   bool in_destructor_;
 
   ObserverList<DesktopObserver> observers_;
 
   ScreenAura* screen_;
 
   // The capture window. When not-null, this window receives all the mouse and
   // touch events.
   Window* capture_window_;
 
   Window* mouse_pressed_handler_;
   Window* mouse_moved_handler_;
   Window* focused_window_;
   Window* touch_event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(Desktop);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_DESKTOP_H_