Update from https://crrev.com/317530

cc/input/scroll_elasticity_helper.cc

 // Copyright 2014 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/input/scroll_elasticity_helper.h"
 
 #include "cc/layers/layer_impl.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/layer_tree_impl.h"
 
 namespace cc {
 
 class ScrollElasticityHelperImpl : public ScrollElasticityHelper {
  public:
   explicit ScrollElasticityHelperImpl(LayerTreeHostImpl* layer_tree_host_impl);
   ~ScrollElasticityHelperImpl() override;
 
+  bool IsUserScrollable() const override;
   gfx::Vector2dF StretchAmount() const override;
   void SetStretchAmount(const gfx::Vector2dF& stretch_amount) override;
   gfx::ScrollOffset ScrollOffset() const override;
   gfx::ScrollOffset MaxScrollOffset() const override;
   void ScrollBy(const gfx::Vector2dF& delta) override;
   void RequestAnimate() override;
 
  private:
   LayerTreeHostImpl* layer_tree_host_impl_;
 };
 
 ScrollElasticityHelperImpl::ScrollElasticityHelperImpl(
     LayerTreeHostImpl* layer_tree)
     : layer_tree_host_impl_(layer_tree) {
 }
 
 ScrollElasticityHelperImpl::~ScrollElasticityHelperImpl() {
 }
 
+bool ScrollElasticityHelperImpl::IsUserScrollable() const {
+  LayerImpl* layer = layer_tree_host_impl_->OuterViewportScrollLayer();
+  if (!layer)
+    return false;
+  return layer->user_scrollable_horizontal() ||
+         layer->user_scrollable_vertical();
+}
+
 gfx::Vector2dF ScrollElasticityHelperImpl::StretchAmount() const {
   return layer_tree_host_impl_->active_tree()->elastic_overscroll()->Current(
       true);
 }
 
 void ScrollElasticityHelperImpl::SetStretchAmount(
     const gfx::Vector2dF& stretch_amount) {
   if (stretch_amount == StretchAmount())
     return;
 
@@ skipping 26 matching lines @@
   layer_tree_host_impl_->SetNeedsAnimate();
 }
 
 // static
 ScrollElasticityHelper* ScrollElasticityHelper::CreateForLayerTreeHostImpl(
     LayerTreeHostImpl* layer_tree_host_impl) {
   return new ScrollElasticityHelperImpl(layer_tree_host_impl);
 }
 
 }  // namespace cc