Add support for latency measurement to Telemetry smoothness benchmarks.

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 0d67af1cd55ca3639c64c1052e93152cdb680955..4df4ab3cc3d118aa129a677de932d6b0ec1b4654 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -25,6 +25,7 @@
 #include "build/build_config.h"
 #include "content/browser/renderer_host/event_with_latency_info.h"
 #include "content/browser/renderer_host/smooth_scroll_gesture_controller.h"
+#include "content/common/browser_rendering_stats.h"
 #include "content/common/view_message_enums.h"
 #include "content/port/common/input_event_ack_state.h"
 #include "content/public/browser/render_widget_host.h"
@@ -916,6 +917,8 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
 
   int64 last_input_number_;
 
+  BrowserRenderingStats rendering_stats_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };