Support dynamic switching between integrated and discrete GPUs on Mac OS X.

ui/gfx/gl/gl_context_glx.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.
 
 #include <string>
 
 #include "ui/gfx/gl/gl_context.h"
 
 namespace gfx {
 
 class GLSurface;
 
 // Encapsulates a GLX OpenGL context.
 class GLContextGLX : public GLContext {
  public:
   explicit GLContextGLX(GLShareGroup* share_group);
   virtual ~GLContextGLX();
 
   // Implement GLContext.
-  virtual bool Initialize(GLSurface* compatible_surface);
+  virtual bool Initialize(
+      GLSurface* compatible_surface, GpuPreference gpu_preference);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
   virtual bool IsCurrent(GLSurface* surface);
   virtual void* GetHandle();
   virtual void SetSwapInterval(int interval);
   virtual std::string GetExtensions();
   virtual bool WasAllocatedUsingARBRobustness();
 
  private:
   void* context_;
 
   DISALLOW_COPY_AND_ASSIGN(GLContextGLX);
 };
 
 }  // namespace gfx