use preferDiscreteGpu attribute in WebGraphicsContext3D initialization

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

 // Copyright (c) 2012 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 "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 74 matching lines @@
 }
 
 bool WebGraphicsContext3DCommandBufferImpl::Initialize(
     const WebGraphicsContext3D::Attributes& attributes) {
   DCHECK(!context_);
   TRACE_EVENT0("gpu", "WebGfxCtx3DCmdBfrImpl::initialize");
   GpuChannelHostFactory* factory = GpuChannelHostFactory::instance();
   if (!factory)
     return false;
 
-  // The noExtensions and canRecoverFromContextLoss flags are
-  // currently used as hints that we are creating a context on
-  // behalf of WebGL or accelerated 2D canvas, respectively.
-  if (attributes.noExtensions || !attributes.canRecoverFromContextLoss)
+  if (attributes.preferDiscreteGPU)
     gpu_preference_ = gfx::PreferDiscreteGpu;
 
   bool retry = false;
 
   // Note similar code in Pepper PlatformContext3DImpl::Init.
   do {
     host_ = factory->EstablishGpuChannelSync(
         content::
         CAUSE_FOR_GPU_LAUNCH_WEBGRAPHICSCONTEXT3DCOMMANDBUFFERIMPL_INITIALIZE);
     if (!host_)
@@ skipping 1098 matching lines @@
 }
 
 void WebGraphicsContext3DCommandBufferImpl::OnErrorMessage(
     const std::string& message, int id) {
   if (error_message_callback_) {
     WebKit::WebString str = WebKit::WebString::fromUTF8(message.c_str());
     error_message_callback_->onErrorMessage(str, id);
   }
 }