Add latency measurement system

content/common/gpu/gpu_command_buffer_stub.h

Index: content/common/gpu/gpu_command_buffer_stub.h
diff --git a/content/common/gpu/gpu_command_buffer_stub.h b/content/common/gpu/gpu_command_buffer_stub.h
index 0519e8c7fd0f30e967e4d8cdc68f5c7d04c4207e..166e30c33e49b743fa63fd4e1a1ff1a340ff9d86 100644
--- a/content/common/gpu/gpu_command_buffer_stub.h
+++ b/content/common/gpu/gpu_command_buffer_stub.h
@@ -28,6 +28,7 @@
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/gpu_preference.h"
 #include "ui/surface/transport_dib.h"
+#include "webkit/compositor_bindings/web_latency_info_impl.h"
 
 #if defined(OS_MACOSX)
 #include "ui/surface/accelerated_surface_mac.h"
@@ -62,6 +63,9 @@ class GpuCommandBufferStub
     virtual ~DestructionObserver() {}
   };
 
+  typedef base::Callback<void(const WebKit::WebLatencyInfoImpl&)>
+      LatencyInfoCallback;
+
   GpuCommandBufferStub(
       GpuChannel* channel,
       GpuCommandBufferStub* share_group,
@@ -132,6 +136,10 @@ class GpuCommandBufferStub
 
   void SetPreemptByCounter(scoped_refptr<gpu::RefCountedCounter> counter);
 
+  void SetLatencyInfoCallback(const LatencyInfoCallback& callback);
+
+  void SetLatencyInfo(const WebKit::WebLatencyInfoImpl& latency_info);
+
  private:
   GpuMemoryManager* GetMemoryManager();
   bool MakeCurrent();
@@ -185,6 +193,7 @@ class GpuCommandBufferStub
 
   void OnCommandProcessed();
   void OnParseError();
+  void OnSetLatencyInfo(const WebKit::WebLatencyInfoImpl& latency_info);
 
   void ReportState();
 
@@ -246,6 +255,8 @@ class GpuCommandBufferStub
 
   scoped_refptr<gpu::RefCountedCounter> preempt_by_counter_;
 
+  LatencyInfoCallback latency_info_callback_;
+
   GURL active_url_;
   size_t active_url_hash_;