Break down end-to-end scroll update latency UMA metrics

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 <utility>
 #include <vector>
 
@@ skipping 17 matching lines @@
   // The original timestamp of the touch event which converts to scroll update.
   INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT,
   // The original timestamp of the touch event which converts to the *first*
   // scroll update in a scroll gesture sequence.
   INPUT_EVENT_LATENCY_FIRST_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,
   // This is special component indicating there is rendering scheduled for
-  // the event associated with this LatencyInfo.
-  INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT,
+  // the event associated with this LatencyInfo on main thread.
+  INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
+  // This is special component indicating there is rendering scheduled for
+  // the event associated with this LatencyInfo on impl thread.
+  INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
   // Timestamp when a scroll update is forwarded to the main thread.
   INPUT_EVENT_LATENCY_FORWARD_SCROLL_UPDATE_TO_MAIN_COMPONENT,
   // Timestamp when the event's ack is received by the RWH.
   INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
   // Frame number when a window snapshot was requested. The snapshot
   // is taken when the rendering results actually reach the screen.
   WINDOW_SNAPSHOT_FRAME_NUMBER_COMPONENT,
   // Frame number for a snapshot requested via
   // gpuBenchmarking.beginWindowSnapshotPNG
   // TODO(vkuzkokov): remove when patch adding this hits Stable
   WINDOW_OLD_SNAPSHOT_FRAME_NUMBER_COMPONENT,
   // Timestamp when a tab is requested to be shown.
   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 gpu service began swap buffers, unlike
   // INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT which measures after.
   INPUT_EVENT_GPU_SWAP_BUFFER_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.
@@ skipping 36 matching lines @@
 
   struct EVENTS_BASE_EXPORT InputCoordinate {
     InputCoordinate();
     InputCoordinate(float x, float y);
 
     float x;
     float y;
   };
 
   // Empirically determined constant based on a typical scroll sequence.
-  enum { kTypicalMaxComponentsPerLatencyInfo = 9 };
+  enum { kTypicalMaxComponentsPerLatencyInfo = 10 };
 
   enum { kMaxInputCoordinates = 2 };
 
   // Map a Latency Component (with a component-specific int64 id) to a
   // component info.
   typedef base::SmallMap<
       std::map<std::pair<LatencyComponentType, int64>, LatencyComponent>,
       kTypicalMaxComponentsPerLatencyInfo> LatencyMap;
 
   LatencyInfo();
@@ skipping 52 matching lines @@
 
   // 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_