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

gpu/command_buffer/client/gles2_demo.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.
 
 // This file implements a standalone executable demo of using GLES2 over
 // command buffers. This code is temporary as the setup that happens
 // here is in a state of flux. Eventually there will be several versions of
 // setup, one for trusted code, one for pepper, one for NaCl, and maybe others.
 
 #include <windows.h>
@@ skipping 50 matching lines @@
                                  gfx::Size(),
                                  gpu::gles2::DisallowedExtensions(),
                                  NULL,
                                  std::vector<int32>(),
                                  NULL,
                                  0)) {
     return NULL;
   }
 
   command_buffer->SetPutOffsetChangeCallback(
-      NewCallback(gpu_scheduler, &GpuScheduler::ProcessCommands));
+      NewCallback(gpu_scheduler, &GpuScheduler::PutChanged));
 
   GLES2CmdHelper* helper = new GLES2CmdHelper(command_buffer.get());
   if (!helper->Initialize(size)) {
     // TODO(gman): cleanup.
     return false;
   }
 
   size_t transfer_buffer_size = 512 * 1024;
   int32 transfer_buffer_id =
       command_buffer->CreateTransferBuffer(transfer_buffer_size, -1);
@@ skipping 139 matching lines @@
     ::fprintf(stdout, "Could not setup window.\n");
     return EXIT_FAILURE;
   }
 
   demo->Setup(hwnd, kCommandBufferSize);
 
   ProcessMessages(hwnd);
 
   return EXIT_SUCCESS;
 }