gpu: Fix corrupted state due to virtual MakeCurrent race.

gpu/command_buffer/service/gl_state_restorer_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 "gpu/command_buffer/service/gl_state_restorer_impl.h"
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 namespace gpu {
 
 GLStateRestorerImpl::GLStateRestorerImpl(
     base::WeakPtr<gles2::GLES2Decoder> decoder)
     : decoder_(decoder) {
 }
 
 GLStateRestorerImpl::~GLStateRestorerImpl() {
 }
 
+bool GLStateRestorerImpl::IsInitialized() {
+  DCHECK(decoder_.get());
+  return decoder_->initialized();
+}
+
 void GLStateRestorerImpl::RestoreState() {
   DCHECK(decoder_.get());
   decoder_->RestoreState();
 }
 
 void GLStateRestorerImpl::RestoreAllTextureUnitBindings() {
   DCHECK(decoder_.get());
   decoder_->RestoreAllTextureUnitBindings();
 }
 
 void GLStateRestorerImpl::RestoreFramebufferBindings() {
   DCHECK(decoder_.get());
   decoder_->RestoreFramebufferBindings();
 }
 
 }  // namespace gpu