Make CommandBuffer::Flush asynchronous, and add CommandBuffer::FlushSync with former semantics.

gpu/command_buffer/service/command_buffer_service.cc

Index: gpu/command_buffer/service/command_buffer_service.cc
diff --git a/gpu/command_buffer/service/command_buffer_service.cc b/gpu/command_buffer/service/command_buffer_service.cc
index fd443f2e9d341b73d5701f7956d5e5d4de5e05d6..c2a85affc6b361231062a971edf0665f4541a991 100644
--- a/gpu/command_buffer/service/command_buffer_service.cc
+++ b/gpu/command_buffer/service/command_buffer_service.cc
@@ -77,7 +77,7 @@ CommandBufferService::State CommandBufferService::GetState() {
   return state;
 }
 
-CommandBufferService::State CommandBufferService::Flush(int32 put_offset) {
+CommandBufferService::State CommandBufferService::FlushSync(int32 put_offset) {
   if (put_offset < 0 || put_offset > num_entries_) {
     error_ = gpu::error::kOutOfBounds;
     return GetState();
@@ -92,6 +92,10 @@ CommandBufferService::State CommandBufferService::Flush(int32 put_offset) {
   return GetState();
 }
 
+void CommandBufferService::Flush(int32 put_offset) {
+  FlushSync(put_offset);
+}
+
 void CommandBufferService::SetGetOffset(int32 get_offset) {
   DCHECK(get_offset >= 0 && get_offset < num_entries_);
   get_offset_ = get_offset;