gpu: Fix corrupted state due to virtual MakeCurrent race.

gpu/command_buffer/service/gl_state_restorer_impl.cc

Index: gpu/command_buffer/service/gl_state_restorer_impl.cc
diff --git a/gpu/command_buffer/service/gl_state_restorer_impl.cc b/gpu/command_buffer/service/gl_state_restorer_impl.cc
index d39b805f0bc89eb946a1e5aacbc83e31dabaf781..7b3c5ed384148318cde872d3a1c343ccb488feab 100644
--- a/gpu/command_buffer/service/gl_state_restorer_impl.cc
+++ b/gpu/command_buffer/service/gl_state_restorer_impl.cc
@@ -16,6 +16,11 @@ GLStateRestorerImpl::GLStateRestorerImpl(
 GLStateRestorerImpl::~GLStateRestorerImpl() {
 }
 
+bool GLStateRestorerImpl::IsInitialized() {
+  DCHECK(decoder_.get());
+  return decoder_->initialized();
+}
+
 void GLStateRestorerImpl::RestoreState() {
   DCHECK(decoder_.get());
   decoder_->RestoreState();