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

ui/events/blink/input_handler_proxy.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_BLINK_INPUT_HANDLER_PROXY_H_
 #define UI_EVENTS_BLINK_INPUT_HANDLER_PROXY_H_
 
 #include <memory>
 
 #include "base/containers/hash_tables.h"
@@ skipping 39 matching lines @@
 
   enum EventDisposition {
     DID_HANDLE,
     DID_NOT_HANDLE,
     DID_HANDLE_NON_BLOCKING,
     DROP_EVENT
   };
   EventDisposition HandleInputEventWithLatencyInfo(
       const blink::WebInputEvent& event,
       ui::LatencyInfo* latency_info);
-  EventDisposition HandleInputEvent(const blink::WebInputEvent& event);
+  EventDisposition HandleInputEvent(const blink::WebInputEvent& event,
+                                    ui::LatencyInfo* latency_info = nullptr);
 
   // cc::InputHandlerClient implementation.
   void WillShutdown() override;
   void Animate(base::TimeTicks time) override;
   void MainThreadHasStoppedFlinging() override;
   void ReconcileElasticOverscrollAndRootScroll() override;
   void UpdateRootLayerStateForSynchronousInputHandler(
       const gfx::ScrollOffset& total_scroll_offset,
       const gfx::ScrollOffset& max_scroll_offset,
       const gfx::SizeF& scrollable_size,
@@ skipping 25 matching lines @@
  private:
   friend class test::InputHandlerProxyTest;
 
   // Helper functions for handling more complicated input events.
   EventDisposition HandleMouseWheel(
       const blink::WebMouseWheelEvent& event);
   EventDisposition ScrollByMouseWheel(const blink::WebMouseWheelEvent& event);
   EventDisposition HandleGestureScrollBegin(
       const blink::WebGestureEvent& event);
   EventDisposition HandleGestureScrollUpdate(
-      const blink::WebGestureEvent& event);
+      const blink::WebGestureEvent& event,
+      ui::LatencyInfo* latency_info);
   EventDisposition HandleGestureScrollEnd(
       const blink::WebGestureEvent& event);
   EventDisposition HandleGestureFlingStart(
       const blink::WebGestureEvent& event);
   EventDisposition HandleTouchStart(const blink::WebTouchEvent& event);
   EventDisposition HandleTouchMove(const blink::WebTouchEvent& event);
   EventDisposition HandleTouchEnd(const blink::WebTouchEvent& event);
 
   // Returns true if the event should be suppressed due to to an active,
   // boost-enabled fling, in which case further processing should cease.
@@ skipping 91 matching lines @@
   int32_t touch_start_result_;
 
   base::TimeTicks last_fling_animate_time_;
 
   DISALLOW_COPY_AND_ASSIGN(InputHandlerProxy);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_BLINK_INPUT_HANDLER_PROXY_H_