Update from https://crrev.com/312398

cc/layers/layer.cc

 // Copyright 2010 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/layers/layer.h"
 
 #include <algorithm>
 
 #include "base/atomic_sequence_num.h"
 #include "base/debug/trace_event.h"
@@ skipping 53 matching lines @@
       hide_layer_and_subtree_(false),
       masks_to_bounds_(false),
       contents_opaque_(false),
       double_sided_(true),
       should_flatten_transform_(true),
       use_parent_backface_visibility_(false),
       draw_checkerboard_for_missing_tiles_(false),
       force_render_surface_(false),
       transform_is_invertible_(true),
       has_render_surface_(false),
+      clear_impl_scroll_delta_(false),
       background_color_(0),
       opacity_(1.f),
       blend_mode_(SkXfermode::kSrcOver_Mode),
       scroll_parent_(nullptr),
       clip_parent_(nullptr),
       replica_layer_(nullptr),
       raster_scale_(0.f),
       client_(nullptr) {
   layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
   layer_animation_controller_->AddValueObserver(this);
@@ skipping 879 matching lines @@
     layer->SetClipChildren(clip_children);
   } else {
     layer->SetClipChildren(nullptr);
   }
 
   // Adjust the scroll delta to be just the scrolls that have happened since
   // the BeginMainFrame was sent.  This happens for impl-side painting
   // in LayerImpl::ApplyScrollDeltasSinceBeginMainFrame in a separate tree walk.
   if (layer->layer_tree_impl()->settings().impl_side_painting) {
     layer->SetScrollOffset(scroll_offset_);
+    if (clear_impl_scroll_delta_)
+      layer->ClearScrollDeltaAtActivation();
   } else {
-    layer->SetScrollOffsetAndDelta(
-        scroll_offset_,
-        layer->ScrollDelta() - layer->sent_scroll_delta());
+    if (clear_impl_scroll_delta_) {
+      layer->SetScrollOffsetAndDelta(scroll_offset_, gfx::Vector2dF());
+    } else {
+      layer->SetScrollOffsetAndDelta(
+          scroll_offset_, layer->ScrollDelta() - layer->sent_scroll_delta());
+    }
     layer->SetSentScrollDelta(gfx::Vector2dF());
   }
+  clear_impl_scroll_delta_ = false;
 
   // Wrap the copy_requests_ in a PostTask to the main thread.
   ScopedPtrVector<CopyOutputRequest> main_thread_copy_requests;
   for (ScopedPtrVector<CopyOutputRequest>::iterator it = copy_requests_.begin();
        it != copy_requests_.end();
        ++it) {
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner =
         layer_tree_host()->proxy()->MainThreadTaskRunner();
     scoped_ptr<CopyOutputRequest> original_request = copy_requests_.take(it);
     const CopyOutputRequest& original_request_ref = *original_request;
@@ skipping 149 matching lines @@
   // Do nothing. Scroll deltas will be sent from the compositor thread back
   // to the main thread in the same manner as during non-animated
   // compositor-driven scrolling.
 }
 
 void Layer::OnAnimationWaitingForDeletion() {
   // Animations are only deleted during PushProperties.
   SetNeedsPushProperties();
 }
 
+void Layer::OnScrollOffsetAnimationRemoved() {
+  clear_impl_scroll_delta_ = true;
+}
+
 bool Layer::IsActive() const {
   return true;
 }
 
 bool Layer::AddAnimation(scoped_ptr <Animation> animation) {
   if (!layer_animation_controller_->animation_registrar())
     return false;
 
   if (animation->target_property() == Animation::ScrollOffset &&
       !layer_animation_controller_->animation_registrar()
@@ skipping 119 matching lines @@
     const TransformNode* node = tree.Node(transform_tree_index());
     gfx::Transform ssxform;
     tree.ComputeTransform(node->id, node->data.target_id, &ssxform);
     xform.ConcatTransform(ssxform);
   }
   xform.Scale(1.0 / contents_scale_x(), 1.0 / contents_scale_y());
   return xform;
 }
 
 }  // namespace cc