ozone: Initialize a subsystem only if necessary.

ui/gfx/ozone/surface_factory_ozone.h

 // Copyright (c) 2013 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_GFX_OZONE_SURFACE_LNUX_FACTORY_OZONE_H_
 #define UI_GFX_OZONE_SURFACE_LNUX_FACTORY_OZONE_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/native_library.h"
@@ skipping 64 matching lines @@
   };
 
   typedef void*(*GLGetProcAddressProc)(const char* name);
   typedef base::Callback<void(base::NativeLibrary)> AddGLLibraryCallback;
   typedef base::Callback<void(GLGetProcAddressProc)>
       SetGLGetProcAddressProcCallback;
 
   SurfaceFactoryOzone();
   virtual ~SurfaceFactoryOzone();
 
-  // Returns the instance
+  // Returns the singleton instance.
   static SurfaceFactoryOzone* GetInstance();
 
-  // Sets the implementation delegate. Ownership is retained by the caller.
-  static void SetInstance(SurfaceFactoryOzone* impl);
-
   // Configures the display hardware. Must be called from within the GPU
   // process before the sandbox has been activated.
   virtual HardwareState InitializeHardware() = 0;
 
   // Cleans up display hardware state. Call this from within the GPU process.
   // This method must be safe to run inside of the sandbox.
   virtual void ShutdownHardware() = 0;
 
   // Returns native platform display handle. This is used to obtain the EGL
   // display connection for the native display.
@@ skipping 56 matching lines @@
   virtual gfx::NativeBufferOzone CreateNativeBuffer(gfx::Size size,
                                                     BufferFormat format);
 
  private:
   static SurfaceFactoryOzone* impl_; // not owned
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_OZONE_SURFACE_LNUX_FACTORY_OZONE_H_