re-land the "SourceEventType added to LatencyInfo."

content/browser/renderer_host/input/mouse_wheel_event_queue.cc

 // Copyright 2016 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.
 
 #include "content/browser/renderer_host/input/mouse_wheel_event_queue.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/events/blink/web_input_event_traits.h"
@@ skipping 173 matching lines @@
         // If no GSB has been sent, it will be a non-synthetic GSB.
         SendScrollBegin(scroll_update, false);
       } else if (has_phase_info && !enable_scroll_latching_) {
         // If a GSB has been sent, generate a synthetic GSB if we have phase
         // information. This should be removed once crbug.com/526463 is fully
         // implemented.
         SendScrollBegin(scroll_update, true);
       }
 
       if (needs_update) {
-        ui::LatencyInfo latency = ui::LatencyInfo();
+        ui::LatencyInfo latency = ui::LatencyInfo(ui::SourceEventType::WHEEL);
         latency.AddLatencyNumber(
             ui::INPUT_EVENT_LATENCY_GENERATE_SCROLL_UPDATE_FROM_MOUSE_WHEEL, 0,
             0);
         client_->ForwardGestureEventWithLatencyInfo(scroll_update, latency);
       }
 
       if (current_phase_ended) {
         // Non-synthetic GSEs are sent when the current phase is canceled or
         // ended.
         SendScrollEnd(scroll_update, false);
@@ skipping 67 matching lines @@
   scroll_end.data.scrollEnd.deltaUnits =
       update_event.data.scrollUpdate.deltaUnits;
 
   if (!synthetic) {
     needs_scroll_begin_ = true;
     needs_scroll_end_ = false;
 
     if (scroll_end_timer_.IsRunning())
       scroll_end_timer_.Reset();
   }
-  client_->ForwardGestureEventWithLatencyInfo(scroll_end, ui::LatencyInfo());
+  client_->ForwardGestureEventWithLatencyInfo(
+      scroll_end, ui::LatencyInfo(ui::SourceEventType::WHEEL));
 }
 
 void MouseWheelEventQueue::SendScrollBegin(
     const WebGestureEvent& gesture_update,
     bool synthetic) {
   DCHECK((synthetic && !needs_scroll_begin_) || needs_scroll_begin_);
 
   WebGestureEvent scroll_begin(gesture_update);
   scroll_begin.type = WebInputEvent::GestureScrollBegin;
   scroll_begin.data.scrollBegin.synthetic = synthetic;
   scroll_begin.data.scrollBegin.inertialPhase =
       gesture_update.data.scrollUpdate.inertialPhase;
   scroll_begin.data.scrollBegin.deltaXHint =
       gesture_update.data.scrollUpdate.deltaX;
   scroll_begin.data.scrollBegin.deltaYHint =
       gesture_update.data.scrollUpdate.deltaY;
   scroll_begin.data.scrollBegin.targetViewport = false;
   scroll_begin.data.scrollBegin.deltaHintUnits =
       gesture_update.data.scrollUpdate.deltaUnits;
 
   needs_scroll_begin_ = false;
   needs_scroll_end_ = true;
-  client_->ForwardGestureEventWithLatencyInfo(scroll_begin, ui::LatencyInfo());
+  client_->ForwardGestureEventWithLatencyInfo(
+      scroll_begin, ui::LatencyInfo(ui::SourceEventType::WHEEL));
 }
 
 }  // namespace content