Update from https://crrev.com/307330

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 361fae14285e58f5675126d4a16d9b1338a79e11..22b11967e6f0795b186e0f70e5ae3ea5d317b12a 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -363,6 +363,9 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
 
   sync_tree->PushPageScaleFromMainThread(
       page_scale_factor_, min_page_scale_factor_, max_page_scale_factor_);
+  sync_tree->elastic_overscroll()->PushFromMainThread(elastic_overscroll_);
+  if (sync_tree->IsActiveTree())
+    sync_tree->elastic_overscroll()->PushPendingToActive();
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 
@@ -875,6 +878,7 @@ bool LayerTreeHost::UpdateLayers(Layer* root_layer,
     LayerTreeHostCommon::CalcDrawPropsMainInputs inputs(
         root_layer, device_viewport_size(), gfx::Transform(),
         device_scale_factor_, page_scale_factor_, page_scale_layer,
+        elastic_overscroll_, overscroll_elasticity_layer_.get(),
         GetRendererCapabilities().max_texture_size, settings_.can_use_lcd_text,
         settings_.layers_always_allowed_lcd_text,
         can_render_to_separate_surface,
@@ -1126,9 +1130,8 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   }
 
   if (!inner_viewport_scroll_delta.IsZero() ||
-      !outer_viewport_scroll_delta.IsZero() ||
-      info->page_scale_delta != 1.f ||
-      info->top_controls_delta) {
+      !outer_viewport_scroll_delta.IsZero() || info->page_scale_delta != 1.f ||
+      !info->elastic_overscroll_delta.IsZero() || info->top_controls_delta) {
     // Preemptively apply the scroll offset and scale delta here before sending
     // it to the client.  If the client comes back and sets it to the same
     // value, then the layer can early out without needing a full commit.
@@ -1147,12 +1150,15 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
     }
 
     ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
+    elastic_overscroll_ += info->elastic_overscroll_delta;
     if (!settings_.use_pinch_virtual_viewport) {
       client_->ApplyViewportDeltas(
           inner_viewport_scroll_delta + outer_viewport_scroll_delta,
           info->page_scale_delta,
           info->top_controls_delta);
     } else {
+      // TODO(ccameron): pass the elastic overscroll here so that input events
+      // may be translated appropriately.
       client_->ApplyViewportDeltas(
           inner_viewport_scroll_delta,
           outer_viewport_scroll_delta,