Take MT jank into account when animating the scroll offset on CC

ui/events/blink/input_handler_proxy.cc

 // 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.
 
 #include "ui/events/blink/input_handler_proxy.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 258 matching lines @@
     ReportInputEventLatencyUma(event, *latency_info);
 
   TRACE_EVENT_WITH_FLOW1("input,benchmark",
                          "LatencyInfo.Flow",
                          TRACE_ID_DONT_MANGLE(latency_info->trace_id()),
                          TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT,
                          "step", "HandleInputEventImpl");
 
   std::unique_ptr<cc::SwapPromiseMonitor> latency_info_swap_promise_monitor =
       input_handler_->CreateLatencyInfoSwapPromiseMonitor(latency_info);
-  InputHandlerProxy::EventDisposition disposition = HandleInputEvent(event);
+  InputHandlerProxy::EventDisposition disposition =
+      HandleInputEvent(event, latency_info);
   return disposition;
 }
 
 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleInputEvent(
-    const WebInputEvent& event) {
+    const WebInputEvent& event, ui::LatencyInfo* latency_info) {
   DCHECK(input_handler_);
 
   if (FilterInputEventForFlingBoosting(event))
     return DID_HANDLE;
 
   switch (event.type) {
     case WebInputEvent::MouseWheel:
       return HandleMouseWheel(static_cast<const WebMouseWheelEvent&>(event));
 
     case WebInputEvent::GestureScrollBegin:
       return HandleGestureScrollBegin(
           static_cast<const WebGestureEvent&>(event));
 
     case WebInputEvent::GestureScrollUpdate:
       return HandleGestureScrollUpdate(
-          static_cast<const WebGestureEvent&>(event));
+          static_cast<const WebGestureEvent&>(event), latency_info);
 
     case WebInputEvent::GestureScrollEnd:
       return HandleGestureScrollEnd(static_cast<const WebGestureEvent&>(event));
 
     case WebInputEvent::GesturePinchBegin: {
       DCHECK(!gesture_pinch_on_impl_thread_);
       const WebGestureEvent& gesture_event =
           static_cast<const WebGestureEvent&>(event);
       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad &&
           input_handler_->GetEventListenerProperties(
@@ skipping 329 matching lines @@
   }
   if (scroll_elasticity_controller_ && result != DID_NOT_HANDLE)
     HandleScrollElasticityOverscroll(gesture_event,
                                      cc::InputHandlerScrollResult());
 
   return result;
 }
 
 InputHandlerProxy::EventDisposition
 InputHandlerProxy::HandleGestureScrollUpdate(
-  const WebGestureEvent& gesture_event) {
+  const WebGestureEvent& gesture_event, ui::LatencyInfo* latency_info) {
 #ifndef NDEBUG
   DCHECK(expect_scroll_update_end_);
 #endif
   if (!gesture_scroll_on_impl_thread_ && !gesture_pinch_on_impl_thread_)
     return DID_NOT_HANDLE;
 
   cc::ScrollState scroll_state = CreateScrollStateForGesture(gesture_event);
   gfx::Point scroll_point(gesture_event.x, gesture_event.y);
   gfx::Vector2dF scroll_delta(-gesture_event.data.scrollUpdate.deltaX,
                               -gesture_event.data.scrollUpdate.deltaY);
 
   if (ShouldAnimate(gesture_event.data.scrollUpdate.deltaUnits !=
                     blink::WebGestureEvent::ScrollUnits::Pixels)) {
     switch (input_handler_->ScrollAnimated(scroll_point, scroll_delta).thread) {
-      case cc::InputHandler::SCROLL_ON_IMPL_THREAD:
+      case cc::InputHandler::SCROLL_ON_IMPL_THREAD: {
+        for (const auto& lc : latency_info->latency_components()) {
+          if (lc.first.first == ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT) {
+            LatencyInfo::LatencyComponent o_component;
+            if (latency_info->FindLatency(
+                ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT, 0, &o_component)) {
+              input_handler_->AdjustDuration(
+                lc.second.event_time - o_component.event_time);

[skobes, 2016/06/08 22:47:28]

I don't really understand what this is doing, is it equivalent to using
WebInputEvent::timeStampSeconds?

+            }
+            break;
+          }
+        }
         return DID_HANDLE;
+      }
       case cc::InputHandler::SCROLL_IGNORED:
         return DROP_EVENT;
       default:
         return DID_NOT_HANDLE;
     }
   }
   cc::InputHandlerScrollResult scroll_result =
       input_handler_->ScrollBy(&scroll_state);
   HandleOverscroll(scroll_point, scroll_result);
 
@@ skipping 686 matching lines @@
   // is made asynchronously, to minimize divergence between main thread and
   // impl thread event handling paths.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&InputScrollElasticityController::ObserveGestureEventAndResult,
                  scroll_elasticity_controller_->GetWeakPtr(), gesture_event,
                  scroll_result));
 }
 
 }  // namespace ui