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 56 matching lines @@
   bool OnKeyEvent(const KeyEvent& event);
 
   // Called when the host changes size.
   void OnHostResized(const gfx::Size& size);
 
   // Compositor we're drawing to.
   ui::Compositor* compositor() { return compositor_.get(); }
 
   Window* window() { return window_.get(); }
 
-  static void set_compositor_factory_for_testing(ui::Compositor*(*factory)()) {
-    compositor_factory_ = factory;
-  }
-  static ui::Compositor* (*compositor_factory())() {
-    return compositor_factory_;
-  }
-
   // Sets the active window to |window| and the focused window to |to_focus|.
   // If |to_focus| is NULL, |window| is focused.
   void SetActiveWindow(Window* window, Window* to_focus);
   Window* active_window() { return active_window_; }
 
   // Activates the topmost window. Does nothing if the topmost window is already
   // active.
   void ActivateTopmostWindow();
 
   // Deactivates |window| and activates the topmost window. Does nothing if
@@ skipping 26 matching lines @@
 
   scoped_ptr<internal::RootWindow> window_;
 
   scoped_ptr<DesktopHost> host_;
 
   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_;
 
   DISALLOW_COPY_AND_ASSIGN(Desktop);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_DESKTOP_H_