Remove scroll layer ids from scrollbar layers

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 3657 matching lines @@
   }
   return str;
 }
 
 void LayerTreeHostImpl::RegisterScrollbarAnimationController(
     ElementId scroll_element_id) {
   if (settings().scrollbar_animator == LayerTreeSettings::NO_ANIMATOR)
     return;
   if (ScrollbarAnimationControllerForElementId(scroll_element_id))
     return;
+
   scrollbar_animation_controllers_[scroll_element_id] =
       active_tree_->CreateScrollbarAnimationController(scroll_element_id);
 }
 
 void LayerTreeHostImpl::UnregisterScrollbarAnimationController(
     ElementId scroll_element_id) {
   scrollbar_animation_controllers_.erase(scroll_element_id);
 }
 
 ScrollbarAnimationController*
@@ skipping 582 matching lines @@
 }
 
 void LayerTreeHostImpl::UpdateScrollSourceInfo(bool is_wheel_scroll) {
   if (is_wheel_scroll)
     has_scrolled_by_wheel_ = true;
   else
     has_scrolled_by_touch_ = true;
 }
 
 }  // namespace cc