gpu: Use GpuMemoryBufferManager from GpuService when possible.

services/ui/public/cpp/gpu_service.cc

Index: services/ui/public/cpp/gpu_service.cc
diff --git a/services/ui/public/cpp/gpu_service.cc b/services/ui/public/cpp/gpu_service.cc
index 5951e699a5d5475c99a9f6af8bf17a2116aa2850..0767dfb9d63088d57a4e044a1219690549c819a4 100644
--- a/services/ui/public/cpp/gpu_service.cc
+++ b/services/ui/public/cpp/gpu_service.cc
@@ -102,6 +102,10 @@ scoped_refptr<gpu::GpuChannelHost> GpuService::EstablishGpuChannelSync() {
   return gpu_channel_;
 }
 
+gpu::GpuMemoryBufferManager* GpuService::GetGpuMemoryBufferManager() {
+  return gpu_memory_buffer_manager_.get();
+}
+
 scoped_refptr<gpu::GpuChannelHost> GpuService::GetGpuChannelLocked() {
   if (gpu_channel_ && gpu_channel_->IsLost()) {
     main_task_runner_->PostTask(