Revert of cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

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 3254 matching lines @@
   for (ScrollbarLayerImplBase* scrollbar :
        ScrollbarsFor(scroll_layer_impl->id()))
     distance_to_scrollbar =
         std::min(distance_to_scrollbar,
                  DeviceSpaceDistanceToLayer(device_viewport_point, scrollbar));
 
   animation_controller->DidMouseMoveNear(distance_to_scrollbar /
                                          active_tree_->device_scale_factor());
 }
 
-void LayerTreeHostImpl::MouseLeave() {
-  for (auto& pair : scrollbar_animation_controllers_)
-    pair.second->DidMouseMoveOffScrollbar();
-
-  scroll_layer_id_when_mouse_over_scrollbar_ = Layer::INVALID_ID;
-}
-
 void LayerTreeHostImpl::HandleMouseOverScrollbar(LayerImpl* layer_impl) {
   int new_id = Layer::INVALID_ID;
   if (layer_impl && layer_impl->ToScrollbarLayer())
     new_id = layer_impl->ToScrollbarLayer()->ScrollLayerId();
 
   if (new_id == scroll_layer_id_when_mouse_over_scrollbar_)
     return;
 
   ScrollbarAnimationController* old_animation_controller =
       ScrollbarAnimationControllerForId(
@@ skipping 803 matching lines @@
   if (is_visible) {
     worker_context_visibility_ =
         worker_context->CacheController()->ClientBecameVisible();
   } else {
     worker_context->CacheController()->ClientBecameNotVisible(
         std::move(worker_context_visibility_));
   }
 }
 
 }  // namespace cc