Plumb smooth scrolling in Chromium compositor

cc/trees/layer_tree_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_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 95 matching lines @@
 
   // TODO(vmpstr): Early out if there are no requests on any of the layers. For
   // that, we need to inform LayerTreeImpl whenever there are requests when we
   // get them.
   LayerTreeHostCommon::CallFunctionForSubtree(
       root_layer_.get(), [request_ids](LayerImpl* layer) {
         layer->GatherFrameTimingRequestIds(request_ids);
       });
 }
 
-bool LayerTreeImpl::IsExternalScrollActive() const {
-  return root_layer_scroll_offset_delegate_ &&
-         root_layer_scroll_offset_delegate_->IsExternalScrollActive();
-}
-
 void LayerTreeImpl::DidUpdateScrollOffset(int layer_id) {
   int inner_layer_id = InnerViewportScrollLayer()
                            ? InnerViewportScrollLayer()->id()
                            : Layer::INVALID_ID;
   int outer_layer_id = OuterViewportScrollLayer()
                            ? OuterViewportScrollLayer()->id()
                            : Layer::INVALID_ID;
   if (layer_id != outer_layer_id && layer_id != inner_layer_id)
     return;
 
@@ skipping 1608 matching lines @@
                                                    const gfx::BoxF& box,
                                                    gfx::BoxF* bounds) const {
   *bounds = gfx::BoxF();
   return layer_tree_host_impl_->animation_host()
              ? layer_tree_host_impl_->animation_host()
                    ->TransformAnimationBoundsForBox(layer->id(), box, bounds)
              : true;
 }
 
 }  // namespace cc