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 2729 matching lines @@
 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimatedBegin(
     const gfx::Point& viewport_point) {
   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;
 
-    if (ScrollAnimationUpdateTarget(scroll_node, delta)) {
+    if (ScrollAnimationUpdateTarget(scroll_node, delta, base::TimeDelta())) {
       scroll_status.thread = SCROLL_ON_IMPL_THREAD;
     } else {
       scroll_status.thread = SCROLL_IGNORED;
       scroll_status.main_thread_scrolling_reasons =
           MainThreadScrollingReason::kNotScrollable;
     }
     return scroll_status;
   }
   ScrollStateData scroll_state_data;
   scroll_state_data.position_x = viewport_point.x();
@@ skipping 35 matching lines @@
   gfx::ScrollOffset old_offset =
       scroll_tree.current_scroll_offset(scroll_node->owner_id);
   gfx::ScrollOffset new_offset = scroll_tree.ClampScrollOffsetToLimits(
       old_offset + gfx::ScrollOffset(adjusted_scroll), scroll_node);
 
   gfx::ScrollOffset scrolled = new_offset - old_offset;
   return gfx::Vector2dF(scrolled.x(), scrolled.y());
 }
 
 bool LayerTreeHostImpl::ScrollAnimationCreate(ScrollNode* scroll_node,
-                                              const gfx::Vector2dF& delta) {
+                                              const gfx::Vector2dF& delta,
+                                              base::TimeDelta delayed_by) {
   ScrollTree& scroll_tree = active_tree_->property_trees()->scroll_tree;
 
   const float kEpsilon = 0.1f;
   bool scroll_animated =
       (std::abs(delta.x()) > kEpsilon || std::abs(delta.y()) > kEpsilon);
   if (!scroll_animated) {
     scroll_tree.ScrollBy(scroll_node, delta, active_tree());
     return false;
   }
 
   scroll_tree.set_currently_scrolling_node(scroll_node->id);
 
   gfx::ScrollOffset current_offset =
       scroll_tree.current_scroll_offset(scroll_node->owner_id);
   gfx::ScrollOffset target_offset = scroll_tree.ClampScrollOffsetToLimits(
       current_offset + gfx::ScrollOffset(delta), scroll_node);
   DCHECK_EQ(
       ElementId(active_tree()->LayerById(scroll_node->owner_id)->element_id()),
       scroll_node->element_id);
 
-  animation_host_->ImplOnlyScrollAnimationCreate(scroll_node->element_id,
-                                                 target_offset, current_offset);
+  animation_host_->ImplOnlyScrollAnimationCreate(
+      scroll_node->element_id, target_offset, current_offset, delayed_by);
 
   SetNeedsOneBeginImplFrame();
 
   return true;
 }
 
 InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
     const gfx::Point& viewport_point,
-    const gfx::Vector2dF& scroll_delta) {
+    const gfx::Vector2dF& scroll_delta,
+    base::TimeDelta delayed_by) {
   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;
     if (!scroll_node->user_scrollable_horizontal)
       delta.set_x(0);
     if (!scroll_node->user_scrollable_vertical)
       delta.set_y(0);
 
-    if (ScrollAnimationUpdateTarget(scroll_node, delta)) {
+    if (ScrollAnimationUpdateTarget(scroll_node, delta, delayed_by)) {
       scroll_status.thread = SCROLL_ON_IMPL_THREAD;
     } else {
       scroll_status.thread = SCROLL_IGNORED;
       scroll_status.main_thread_scrolling_reasons =
           MainThreadScrollingReason::kNotScrollable;
     }
     return scroll_status;
   }
 
   ScrollStateData scroll_state_data;
@@ skipping 10 matching lines @@
   if (scroll_status.thread == SCROLL_ON_IMPL_THREAD) {
     gfx::Vector2dF pending_delta = scroll_delta;
     if (scroll_node) {
       for (; scroll_tree.parent(scroll_node);
            scroll_node = scroll_tree.parent(scroll_node)) {
         if (!scroll_node->scrollable ||
             scroll_node->is_outer_viewport_scroll_layer)
           continue;
 
         if (scroll_node->is_inner_viewport_scroll_layer) {
-          gfx::Vector2dF scrolled = viewport()->ScrollAnimated(pending_delta);
+          gfx::Vector2dF scrolled =
+              viewport()->ScrollAnimated(pending_delta, delayed_by);
           // Viewport::ScrollAnimated returns pending_delta as long as it
           // starts an animation.
           if (scrolled == pending_delta)
             return scroll_status;
           pending_delta -= scrolled;
           continue;
         }
 
         gfx::Vector2dF scroll_delta =
             ComputeScrollDelta(scroll_node, pending_delta);
-        if (ScrollAnimationCreate(scroll_node, scroll_delta))
+        if (ScrollAnimationCreate(scroll_node, scroll_delta, delayed_by))
           return scroll_status;
 
         pending_delta -= scroll_delta;
       }
     }
   }
   scroll_state.set_is_ending(true);
   // TODO(Sahel): Once the touchpad scroll latching for Non-mac devices is
   // implemented, the current scrolling layer should not get cleared after
   // each animation (crbug.com/526463).
@@ skipping 1000 matching lines @@
       active_tree_->min_page_scale_factor(),
       active_tree_->max_page_scale_factor());
 }
 
 void LayerTreeHostImpl::ScrollAnimationAbort(LayerImpl* layer_impl) {
   return animation_host_->ScrollAnimationAbort(false /* needs_completion */);
 }
 
 bool LayerTreeHostImpl::ScrollAnimationUpdateTarget(
     ScrollNode* scroll_node,
-    const gfx::Vector2dF& scroll_delta) {
+    const gfx::Vector2dF& scroll_delta,
+    base::TimeDelta delayed_by) {
   DCHECK_EQ(
       ElementId(active_tree()->LayerById(scroll_node->owner_id)->element_id()),
       scroll_node->element_id);
 
   return animation_host_->ImplOnlyScrollAnimationUpdateTarget(
       scroll_node->element_id, scroll_delta,
       active_tree_->property_trees()->scroll_tree.MaxScrollOffset(
           scroll_node->id),
-      CurrentBeginFrameArgs().frame_time);
+      CurrentBeginFrameArgs().frame_time, delayed_by);
 }
 
 bool LayerTreeHostImpl::IsElementInList(ElementId element_id,
                                         ElementListType list_type) const {
   if (list_type == ElementListType::ACTIVE) {
     return active_tree()
                ? active_tree()->LayerByElementId(element_id) != nullptr
                : false;
   } else {
     if (pending_tree() && pending_tree()->LayerByElementId(element_id))
@@ skipping 271 matching lines @@
   if (is_visible) {
     worker_context_visibility_ =
         worker_context->CacheController()->ClientBecameVisible();
   } else {
     worker_context->CacheController()->ClientBecameNotVisible(
         std::move(worker_context_visibility_));
   }
 }
 
 }  // namespace cc