Added GPU Tracing for DoSwapBuffers() to track frames.

gpu/command_buffer/service/gpu_tracer.h

 // 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.
 
 // This file contains the GPUTrace class.
 #ifndef GPU_COMMAND_BUFFER_SERVICE_GPU_TRACER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_GPU_TRACER_H_
 
 #include <string>
 
@@ skipping 195 matching lines @@
   int64 start_time_;
   int64 end_time_;
   GpuTracerType tracer_type_;
   bool end_requested_;
 
   GLuint queries_[2];
 
   DISALLOW_COPY_AND_ASSIGN(GPUTrace);
 };
 
+class ScopedGPUTrace {
+  public:
+    ScopedGPUTrace(GPUTracer* gpu_tracer, GpuTracerSource source,
+                   const std::string& category, const std::string& name)
+        : gpu_tracer_(gpu_tracer),
+          source_(source) {
+      gpu_tracer_->Begin(category, name, source_);
+    }
+
+    ~ScopedGPUTrace() {
+      gpu_tracer_->End(source_);
+    }
+
+   private:
+    GPUTracer* gpu_tracer_;
+    GpuTracerSource source_;
+};
+
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_GPU_TRACER_H_