Added GPU process "echo" IPC message.

gpu/command_buffer/service/gpu_scheduler.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.
 
 #include "gpu/command_buffer/service/gpu_scheduler.h"
 
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
@@ skipping 215 matching lines @@
 
 int32 GpuScheduler::GetGetOffset() {
   return parser_->get();
 }
 
 void GpuScheduler::SetResizeCallback(
     Callback1<gfx::Size>::Type* callback) {
   decoder_->SetResizeCallback(callback);
 }
 
-void GpuScheduler::SetSwapBuffersCallback(
-    Callback0::Type* callback) {
-  wrapped_swap_buffers_callback_.reset(callback);
-  decoder_->SetSwapBuffersCallback(
-      NewCallback(this,
-                  &GpuScheduler::WillSwapBuffers));
-}
-
 void GpuScheduler::SetCommandProcessedCallback(
     Callback0::Type* callback) {
   command_processed_callback_.reset(callback);
 }
 
 GpuScheduler::GpuScheduler(CommandBuffer* command_buffer,
                            gles2::GLES2Decoder* decoder,
                            CommandParser* parser)
     : command_buffer_(command_buffer),
       decoder_(decoder),
       parser_(parser),
       unscheduled_count_(0),
 #if defined(OS_MACOSX)
       swap_buffers_count_(0),
       acknowledged_swap_buffers_count_(0),
 #endif
       method_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 }
 
 }  // namespace gpu