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

ui/gfx/gl/gl_context_glx.cc

 // 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.
 
 extern "C" {
 #include <X11/Xlib.h>
 }
 
 #include "ui/gfx/gl/gl_context_glx.h"
 
@@ skipping 35 matching lines @@
 
 GLContextGLX::GLContextGLX(GLShareGroup* share_group)
   : GLContext(share_group),
     context_(NULL) {
 }
 
 GLContextGLX::~GLContextGLX() {
   Destroy();
 }
 
-bool GLContextGLX::Initialize(GLSurface* compatible_surface) {
+bool GLContextGLX::Initialize(
+    GLSurface* compatible_surface, GpuPreference gpu_preference) {
   GLSurfaceGLX* surface_glx = static_cast<GLSurfaceGLX*>(compatible_surface);
 
   GLXContext share_handle = static_cast<GLXContext>(
       share_group() ? share_group()->GetHandle() : NULL);
 
   if (GLSurfaceGLX::IsCreateContextRobustnessSupported()) {
     DLOG(INFO) << "GLX_ARB_create_context_robustness supported.";
 
     std::vector<int> attribs;
     attribs.push_back(GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB);
@@ skipping 180 matching lines @@
   }
 
   return GLContext::GetExtensions();
 }
 
 bool GLContextGLX::WasAllocatedUsingARBRobustness() {
   return GLSurfaceGLX::IsCreateContextRobustnessSupported();
 }
 
 }  // namespace gfx