cc: Make LayerAnimationController keep state for clearing scroll delta

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index d6e2a236e9827a2c3ce5cfd8b3fca8e32686849f..5bef67d23c99a6dac082b50896964399e9f22df0 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -60,7 +60,6 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       draw_checkerboard_for_missing_tiles_(false),
       draws_content_(false),
       hide_layer_and_subtree_(false),
-      clear_scroll_delta_at_activation_(false),
       transform_is_invertible_(true),
       is_container_for_fixed_position_layers_(false),
       background_color_(0),
@@ -357,10 +356,6 @@ void LayerImpl::SetSentScrollDelta(const gfx::Vector2dF& sent_scroll_delta) {
   sent_scroll_delta_ = sent_scroll_delta;
 }
 
-void LayerImpl::ClearScrollDeltaAtActivation() {
-  clear_scroll_delta_at_activation_ = true;
-}
-
 gfx::Vector2dF LayerImpl::ScrollBy(const gfx::Vector2dF& scroll) {
   gfx::Vector2dF adjusted_scroll = scroll;
   if (layer_tree_impl()->settings().use_pinch_virtual_viewport) {
@@ -549,10 +544,9 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   // Save the difference but clear the sent delta so that we don't subtract
   // it again in SetScrollOffsetAndDelta's pending twin mirroring logic.
   gfx::Vector2dF remaining_delta =
-      clear_scroll_delta_at_activation_
+      layer_animation_controller_->scroll_offset_animation_was_interrupted()
           ? gfx::Vector2dF()
           : layer->ScrollDelta() - layer->sent_scroll_delta();
-  clear_scroll_delta_at_activation_ = false;
 
   layer->SetSentScrollDelta(gfx::Vector2dF());
   layer->SetScrollOffsetAndDelta(scroll_offset_, remaining_delta);
@@ -791,9 +785,6 @@ void LayerImpl::OnScrollOffsetAnimated(const gfx::ScrollOffset& scroll_offset) {
 
 void LayerImpl::OnAnimationWaitingForDeletion() {}
 
-void LayerImpl::OnScrollOffsetAnimationRemoved() {
-}
-
 bool LayerImpl::IsActive() const {
   return layer_tree_impl_->IsActiveTree();
 }
@@ -1174,8 +1165,6 @@ gfx::Vector2dF LayerImpl::ScrollDelta() const {
 }
 
 void LayerImpl::SetScrollDelta(const gfx::Vector2dF& scroll_delta) {
-  if (!IsActive() && clear_scroll_delta_at_activation_)
-    return;
   SetScrollOffsetAndDelta(scroll_offset_, scroll_delta);
 }