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

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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 "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2800 matching lines @@
   gfx::ScrollOffset target_offset = scroll_tree.ClampScrollOffsetToLimits(
       current_offset + gfx::ScrollOffset(delta), scroll_node);
   animation_host_->ImplOnlyScrollAnimationCreate(scroll_node->owner_id,
                                                  target_offset, current_offset);
 
   SetNeedsOneBeginImplFrame();
 
   return true;
 }
 
+void LayerTreeHostImpl::AdjustDuration(base::TimeDelta adjustment) {
+  ScrollTree& scroll_tree = active_tree_->property_trees()->scroll_tree;
+  ScrollNode* scroll_node = scroll_tree.CurrentlyScrollingNode();
+  if (scroll_node) {
+    animation_host_->ImplOnlyScrollAnimationAdjustDuration(
+        scroll_node->owner_id, adjustment);
+  }
+}
+
 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
     const gfx::Point& viewport_point,
     const gfx::Vector2dF& scroll_delta) {
   InputHandler::ScrollStatus scroll_status;
   scroll_status.main_thread_scrolling_reasons =
       MainThreadScrollingReason::kNotScrollingOnMain;
   ScrollTree& scroll_tree = active_tree_->property_trees()->scroll_tree;
   ScrollNode* scroll_node = scroll_tree.CurrentlyScrollingNode();
   if (scroll_node) {
     gfx::Vector2dF delta = scroll_delta;
@@ skipping 1218 matching lines @@
     const {
   return fixed_raster_scale_attempted_scale_change_history_.count() >=
          kFixedRasterScaleAttemptedScaleChangeThreshold;
 }
 
 void LayerTreeHostImpl::SetFixedRasterScaleAttemptedToChangeScale() {
   fixed_raster_scale_attempted_scale_change_history_.set(0);
 }
 
 }  // namespace cc