Added GPU Tracing for DoSwapBuffers() to track frames.

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 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/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 9735 matching lines @@
                        "GLImpl", static_cast<int>(gfx::GetGLImplementation()),
                        "width", (is_offscreen ? offscreen_size_.width() :
                                  surface_->GetSize().width()));
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::DoSwapBuffers",
                "offscreen", is_offscreen,
                "frame", this_frame_number);
   {
     TRACE_EVENT_SYNTHETIC_DELAY("gpu.PresentingFrame");
   }
 
+  struct GPUSwapBufferTrace {
+   public:
+    GPUSwapBufferTrace(GPUTracer* gpu_tracer, int frame)

[vmiura, 2015/01/16 20:39:34]

As discussed offline, maybe make this a generic ScopedGPUTrace class, and remove
'frame' if unused?

[David Yen, 2015/01/16 21:34:19]

Done.

+        : gpu_tracer_(gpu_tracer) {
+      gpu_tracer_->Begin("SwapBuffer", "DoSwapBuffers", kTraceSwapBuffer);
+    }
+
+    ~GPUSwapBufferTrace() {
+      gpu_tracer_->End(kTraceSwapBuffer);
+    }
+
+   private:
+    GPUTracer* gpu_tracer_;
+  } swap_buffer_trace(gpu_tracer_.get(), this_frame_number);
+
   bool is_tracing;
   TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("gpu.debug"),
                                      &is_tracing);
   if (is_tracing) {
     ScopedFrameBufferBinder binder(this, GetBackbufferServiceId());
     gpu_state_tracer_->TakeSnapshotWithCurrentFramebuffer(
         is_offscreen ? offscreen_size_ : surface_->GetSize());
   }
 
   // If offscreen then don't actually SwapBuffers to the display. Just copy
@@ skipping 1874 matching lines @@
   }
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu