Add latency measurement system

cc/layer_tree_host.h

Index: cc/layer_tree_host.h
diff --git a/cc/layer_tree_host.h b/cc/layer_tree_host.h
index 95766e342c4fb8b72c3ae916122a6da4e712e756..c6e0998cba2d0391de0b8f04286019a9d209795e 100644
--- a/cc/layer_tree_host.h
+++ b/cc/layer_tree_host.h
@@ -15,6 +15,7 @@
 #include "base/time.h"
 #include "cc/animation_events.h"
 #include "cc/cc_export.h"
+#include "cc/latency_info.h"
 #include "cc/layer_tree_host_client.h"
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_settings.h"
@@ -105,6 +106,7 @@ public:
     RecreateResult recreateOutputSurface();
     void didCommitAndDrawFrame() { m_client->didCommitAndDrawFrame(); }
     void didCompleteSwapBuffers() { m_client->didCompleteSwapBuffers(); }
+    void onReceivedLatencyInfo(const LatencyInfo& latencyInfo) { m_client->onReceivedLatencyInfo(latencyInfo); }
     void deleteContentsTexturesOnImplThread(ResourceProvider*);
     virtual void acquireLayerTextures();
     // Returns false if we should abort this frame due to initialization failure.
@@ -146,6 +148,8 @@ public:
     void setNeedsRedraw();
     bool commitRequested() const;
 
+    void setLatencyInfo(const LatencyInfo& latency_info);
+
     void setAnimationEvents(scoped_ptr<AnimationEventsVector>, base::Time wallClockTime);
 
     Layer* rootLayer() { return m_rootLayer.get(); }
@@ -279,6 +283,8 @@ private:
 
     static bool s_needsFilterContext;
 
+    LatencyInfo m_latencyInfo;
+
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };