Rework FlushSync to return early if commands have been processed since the last update

gpu/command_buffer/client/gles2_implementation_unittest.cc

Index: gpu/command_buffer/client/gles2_implementation_unittest.cc
diff --git a/gpu/command_buffer/client/gles2_implementation_unittest.cc b/gpu/command_buffer/client/gles2_implementation_unittest.cc
index 5665b96b15ac66d786c64b01967c7ea50b77b1d6..68f2e6bd3a8ac4cd08a955286d187af447773a3e 100644
--- a/gpu/command_buffer/client/gles2_implementation_unittest.cc
+++ b/gpu/command_buffer/client/gles2_implementation_unittest.cc
@@ -50,7 +50,7 @@ class GLES2MockCommandBufferHelper : public CommandBuffer {
     state_.put_offset = put_offset;
   }
 
-  virtual State FlushSync(int32 put_offset) {
+  virtual State FlushSync(int32 put_offset, int32 last_known_get) {
     state_.put_offset = put_offset;
     state_.get_offset = put_offset;
     OnFlush(transfer_buffer_buffer_.ptr);