Report LatencyInfo through trace buffer

ui/events/latency_info.h

Index: ui/events/latency_info.h
diff --git a/ui/events/latency_info.h b/ui/events/latency_info.h
index 8bf56100dfd84324c1dc9b40923244ba580f2400..02f78b7ddf2ca38f21c9b159f46e46e0863bbb82 100644
--- a/ui/events/latency_info.h
+++ b/ui/events/latency_info.h
@@ -15,8 +15,11 @@
 namespace ui {
 
 enum LatencyComponentType {
+  // ---------------------------BEGIN COMPONENT-------------------------------
+  // BEGIN COMPONENT is when we show the latency begin in chrome://tracing.
   // Timestamp when the input event is sent from RenderWidgetHost to renderer.
-  INPUT_EVENT_LATENCY_RWH_COMPONENT,
+  INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
+  // ---------------------------NORMAL COMPONENT-------------------------------
   // Timestamp when the scroll update gesture event is sent from RWH to
   // renderer. In Aura, touch event's LatencyInfo is carried over to the gesture
   // event. So gesture event's INPUT_EVENT_LATENCY_RWH_COMPONENT is the
@@ -30,9 +33,25 @@ enum LatencyComponentType {
   INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
   // Timestamp when the UI event is created.
   INPUT_EVENT_LATENCY_UI_COMPONENT,
-  // Timestamp when the event is acked from renderer. This is currently set
-  // only for touch events.
-  INPUT_EVENT_LATENCY_ACKED_COMPONENT
+  // This is special component indicating there is rendering scheduled for
+  // the event associated with this LatencyInfo.
+  INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT,
+  // Timestamp when the touch event is acked.
+  INPUT_EVENT_LATENCY_ACKED_TOUCH_COMPONENT,
+  // ---------------------------TERMINAL COMPONENT-----------------------------
+  // TERMINAL COMPONENT is when we show the latency end in chrome://tracing.
+  // Timestamp when the mouse event is acked from renderer and it does not
+  // cause any rendering scheduled.
+  INPUT_EVENT_LATENCY_TERMINATED_MOUSE_COMPONENT,
+  // Timestamp when the touch event is acked from renderer and it does not
+  // cause any rendering schedueld and does not generate any gesture event.
+  INPUT_EVENT_LATENCY_TERMINATED_TOUCH_COMPONENT,
+  // Timestamp when the gesture event is acked from renderer, and it does not
+  // cause any rendering schedueld.
+  INPUT_EVENT_LATENCY_TERMINATED_GESTURE_COMPONENT,
+  // Timestamp when the frame is swapped (i.e. when the rendering caused by
+  // input event actually takes effect).
+  INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT,
 };
 
 struct EVENTS_EXPORT LatencyInfo {
@@ -74,7 +93,8 @@ struct EVENTS_EXPORT LatencyInfo {
                                      int64 id,
                                      int64 component_sequence_number,
                                      base::TimeTicks time,
-                                     uint32 event_count);
+                                     uint32 event_count,
+                                     bool dump_to_trace);

[sadrul, 2013/10/10 21:58:38]

Adding a boolean param like this in a public API is discouraged. You would
normally add an enum here instead.

I think LatencyInfo can be cleaned up farther:
 * Hide the member variables.
 * Introduce an internal AddLatencyNumberWithTimestampInternal, that takes in
the bool parameter, and call into that from the public APIs with the appropriate
enum/bool value.
 * Make this a class

This cleanup can happen in a follow-up CL. And if this is cleaned up soon, then
the bool param in this CL should be OK.

[Yufeng Shen (Slow to review), 2013/10/10 22:52:15]

Yes. I am planning to remove the MergeWith() function soon and then the
|dump_to_trace| won't be needed.

 
   // Returns true if the a component with |type| and |id| is found in
   // the latency_components and the component is stored to |output| if
@@ -86,9 +106,10 @@ struct EVENTS_EXPORT LatencyInfo {
   void Clear();
 
   LatencyMap latency_components;
-
-  // This represents the final time that a frame is displayed it.
-  base::TimeTicks swap_timestamp;
+  // The unique id for matching the ASYNC_BEGIN/END trace event.
+  int64 trace_id;
+  // Whether a terminal component has been added.
+  bool terminated;
 };
 
 }  // namespace ui