Splitting up RenderWidgetHostLatencyTracker and some renames.

ui/latency/latency_info.h

Index: ui/latency/latency_info.h
diff --git a/ui/latency/latency_info.h b/ui/latency/latency_info.h
index f34e09ac8ea47f67560820c47c1ed3e261576b0e..b358fbaa69a658cd4e8b71519ed305c16e1c8519 100644
--- a/ui/latency/latency_info.h
+++ b/ui/latency/latency_info.h
@@ -75,9 +75,10 @@ enum LatencyComponentType {
   TAB_SHOW_COMPONENT,
   // Timestamp when the frame is swapped in renderer.
   INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
-  // Timestamp of when the browser process receives a buffer swap notification
-  // from the renderer.
-  INPUT_EVENT_BROWSER_RECEIVED_RENDERER_SWAP_COMPONENT,
+  // Timestamp of when the display compositor receives a compositor frame from
+  // the renderer.
+  // Display compositor can be either in the browser process or in Mus.
+  DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT,
   // Timestamp of when the gpu service began swap buffers, unlike
   // INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT which measures after.
   INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT,
@@ -193,6 +194,12 @@ class LatencyInfo {
                    int64_t id,
                    LatencyComponent* output) const;
 
+  // Returns true if a component with |type| is found in the latency component.
+  // The first such component (when iterating over latency_components_) is
+  // stored to |output| if |output| is not NULL. Returns false if no such
+  // component is found.
+  bool FindLatency(LatencyComponentType type, LatencyComponent* output) const;
+
   void RemoveLatency(LatencyComponentType type);
 
   // Returns true if there is still room for keeping the |input_coordinate|,