Report LatencyInfo through trace buffer

ui/events/latency_info.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_EVENTS_LATENCY_INFO_H_
 #define UI_EVENTS_LATENCY_INFO_H_
 
 #include <map>
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
 #include "ui/events/events_export.h"
 
 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
   // timestamp when its original touch events is sent from RWH to renderer.
   // In non-aura platform, INPUT_EVENT_LATENCY_SCROLL_UPDATE_RWH_COMPONENT
   // is the same as INPUT_EVENT_LATENCY_RWH_COMPONENT.
   INPUT_EVENT_LATENCY_SCROLL_UPDATE_RWH_COMPONENT,
   // The original timestamp of the touch event which converts to scroll update.
   INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT,
   // Original timestamp for input event (e.g. timestamp from kernel).
   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 {
   struct LatencyComponent {
     // Nondecreasing number that can be used to determine what events happened
     // in the component at the time this struct was sent on to the next
     // component.
     int64 sequence_number;
     // Average time of events that happened in this component.
     base::TimeTicks event_time;
@@ skipping 21 matching lines @@
   void AddLatencyNumber(LatencyComponentType component,
                         int64 id,
                         int64 component_sequence_number);
 
   // Modifies the current sequence number and adds a certain number of events
   // for a specific component.
   void AddLatencyNumberWithTimestamp(LatencyComponentType component,
                                      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
   // |output| is not NULL. Returns false if no such component is found.
   bool FindLatency(LatencyComponentType type,
                    int64 id,
                    LatencyComponent* output) const;
 
   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
 
 #endif  // UI_EVENTS_LATENCY_INFO_H_