Update from https://crrev.com/307330

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"
 
@@ skipping 14 matching lines @@
   // TODO(ccameron): This is function is redundant and may be removed.
   return true;
 }
 
 bool ScrollElasticityHelper::AllowsVerticalStretching() {
   // TODO(ccameron): This is function is redundant and may be removed.
   return true;
 }
 
 gfx::Vector2dF ScrollElasticityHelper::StretchAmount() {
+  // TODO(ccameron): Use the value of active_tree->elastic_overscroll directly
   return stretch_offset_;
 }
 
 bool ScrollElasticityHelper::PinnedInDirection(
     const gfx::Vector2dF& direction) {
   gfx::ScrollOffset scroll_offset =
       layer_tree_host_impl_->active_tree()->TotalScrollOffset();
   gfx::ScrollOffset max_scroll_offset =
       layer_tree_host_impl_->active_tree()->TotalMaxScrollOffset();
   bool result = false;
@@ skipping 11 matching lines @@
 bool ScrollElasticityHelper::CanScrollHorizontally() {
   return layer_tree_host_impl_->active_tree()->TotalMaxScrollOffset().x() > 0;
 }
 
 bool ScrollElasticityHelper::CanScrollVertically() {
   return layer_tree_host_impl_->active_tree()->TotalMaxScrollOffset().y() > 0;
 }
 
 gfx::Vector2dF ScrollElasticityHelper::AbsoluteScrollPosition() {
   // TODO(ccameron): This is function is redundant and may be removed.
-  return stretch_offset_;
+  return StretchAmount();
 }
 
 void ScrollElasticityHelper::ImmediateScrollBy(const gfx::Vector2dF& scroll) {
   // TODO(ccameron): This is function is redundant and may be removed.
 }
 
 void ScrollElasticityHelper::ImmediateScrollByWithoutContentEdgeConstraints(
     const gfx::Vector2dF& scroll) {
   stretch_offset_ += scroll;
-
-  // TODO(ccameron): Update the transform of the appropriate layer in the
-  // LayerTreeHostImpl, and request that a frame be drawn.
+  // TODO(ccameron): Use the value of active_tree->elastic_overscroll directly
+  // Note that this assumes that this property's true value is ever changed
+  // by the impl thread. While this is true, it is redundant state.
+  layer_tree_host_impl_->active_tree()->elastic_overscroll()->SetCurrent(
+      -stretch_offset_);
+  layer_tree_host_impl_->active_tree()->set_needs_update_draw_properties();
+  layer_tree_host_impl_->SetNeedsCommit();
+  layer_tree_host_impl_->SetNeedsRedraw();
 }
 
 void ScrollElasticityHelper::StartSnapRubberbandTimer() {
   if (timer_active_)
     return;
   timer_active_ = true;
   layer_tree_host_impl_->SetNeedsAnimate();
 }
 
 void ScrollElasticityHelper::StopSnapRubberbandTimer() {
   timer_active_ = false;
 }
 
 void ScrollElasticityHelper::SnapRubberbandTimerFired() {
   if (timer_active_)
     layer_tree_host_impl_->SetNeedsAnimate();
 }
 
 void ScrollElasticityHelper::AdjustScrollPositionToBoundsIfNecessary() {
   // TODO(ccameron): This is function is redundant and may be removed.
 }
 
 }  // namespace cc