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

gpu/command_buffer/client/cmd_buffer_helper_test.cc

 // Copyright (c) 2011 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.
 
 // Tests for the Command Buffer Helper.
 
 #include "base/callback.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/message_loop.h"
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
@@ skipping 62 matching lines @@
                                 api_mock_.get());
 
     do_jump_command_.reset(new DoJumpCommand(parser_));
     EXPECT_CALL(*api_mock_, DoCommand(cmd::kJump, _, _))
         .WillRepeatedly(
             Invoke(do_jump_command_.get(), &DoJumpCommand::DoCommand));
 
     gpu_scheduler_.reset(new GpuScheduler(
         command_buffer_.get(), NULL, parser_, 1));
     command_buffer_->SetPutOffsetChangeCallback(NewCallback(
-        gpu_scheduler_.get(), &GpuScheduler::ProcessCommands));
+        gpu_scheduler_.get(), &GpuScheduler::PutChanged));
 
     api_mock_->set_engine(gpu_scheduler_.get());
 
     helper_.reset(new CommandBufferHelper(command_buffer_.get()));
     helper_->Initialize(kCommandBufferSizeBytes);
   }
 
   virtual void TearDown() {
     // If the GpuScheduler posts any tasks, this forces them to run.
     MessageLoop::current()->RunAllPending();
@@ skipping 207 matching lines @@
   helper_->Finish();
 
   // Check that the commands did happen.
   Mock::VerifyAndClearExpectations(api_mock_.get());
 
   // Check the error status.
   EXPECT_EQ(error::kNoError, GetError());
 }
 
 }  // namespace gpu