Update from https://crrev.com/315085

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/location.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),
+      scroll_blocks_on_(ScrollBlocksOnNone),
       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),
       frame_timing_requests_dirty_(false) {
   layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
@@ skipping 667 matching lines @@
 }
 
 void Layer::SetTouchEventHandlerRegion(const Region& region) {
   DCHECK(IsPropertyChangeAllowed());
   if (touch_event_handler_region_ == region)
     return;
   touch_event_handler_region_ = region;
   SetNeedsCommit();
 }
 
+void Layer::SetScrollBlocksOn(ScrollBlocksOn scroll_blocks_on) {
+  DCHECK(IsPropertyChangeAllowed());
+  if (scroll_blocks_on_ == scroll_blocks_on)
+    return;
+  scroll_blocks_on_ = scroll_blocks_on;
+  SetNeedsCommit();
+}
+
 void Layer::SetDrawCheckerboardForMissingTiles(bool checkerboard) {
   DCHECK(IsPropertyChangeAllowed());
   if (draw_checkerboard_for_missing_tiles_ == checkerboard)
     return;
   draw_checkerboard_for_missing_tiles_ = checkerboard;
   SetNeedsCommit();
 }
 
 void Layer::SetForceRenderSurface(bool force) {
   DCHECK(IsPropertyChangeAllowed());
@@ skipping 133 matching lines @@
   if (!layer->FilterIsAnimatingOnImplOnly() && !FilterIsAnimating())
     layer->SetFilters(filters_);
   DCHECK(!(FilterIsAnimating() && layer->FilterIsAnimatingOnImplOnly()));
   layer->SetBackgroundFilters(background_filters());
   layer->SetMasksToBounds(masks_to_bounds_);
   layer->SetShouldScrollOnMainThread(should_scroll_on_main_thread_);
   layer->SetHaveWheelEventHandlers(have_wheel_event_handlers_);
   layer->SetHaveScrollEventHandlers(have_scroll_event_handlers_);
   layer->SetNonFastScrollableRegion(non_fast_scrollable_region_);
   layer->SetTouchEventHandlerRegion(touch_event_handler_region_);
+  layer->SetScrollBlocksOn(scroll_blocks_on_);
   layer->SetContentsOpaque(contents_opaque_);
   if (!layer->OpacityIsAnimatingOnImplOnly() && !OpacityIsAnimating())
     layer->SetOpacity(opacity_);
   DCHECK(!(OpacityIsAnimating() && layer->OpacityIsAnimatingOnImplOnly()));
   layer->SetBlendMode(blend_mode_);
   layer->SetIsRootForIsolatedGroup(is_root_for_isolated_group_);
   layer->SetPosition(position_);
   layer->SetIsContainerForFixedPositionLayers(
       IsContainerForFixedPositionLayers());
   layer->SetPositionConstraint(position_constraint_);
@@ skipping 47 matching lines @@
       DCHECK_EQ((*it)->clip_parent(), this);
       LayerImpl* clip_child = layer->layer_tree_impl()->LayerById((*it)->id());
       DCHECK(clip_child);
       clip_children->insert(clip_child);
     }
     layer->SetClipChildren(clip_children);
   } else {
     layer->SetClipChildren(nullptr);
   }
 
-  layer->PushScrollOffsetFromMainThread(scroll_offset_);
-  if (layer_animation_controller_->scroll_offset_animation_was_interrupted() &&
-      layer->IsActive())
-    layer->SetScrollDelta(gfx::Vector2dF());
+  // When a scroll offset animation is interrupted the new scroll position on
+  // the pending tree will clobber any impl-side scrolling occuring on the
+  // active tree. To do so, avoid scrolling the pending tree along with it
+  // instead of trying to undo that scrolling later.
+  if (layer_animation_controller_->scroll_offset_animation_was_interrupted())
+    layer->PushScrollOffsetFromMainThreadAndClobberActiveValue(scroll_offset_);
+  else
+    layer->PushScrollOffsetFromMainThread(scroll_offset_);
   layer->SetScrollCompensationAdjustment(ScrollCompensationAdjustment());
 
   // 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);
@@ skipping 302 matching lines @@
 }
 
 void Layer::SetFrameTimingRequests(
     const std::vector<FrameTimingRequest>& requests) {
   frame_timing_requests_ = requests;
   frame_timing_requests_dirty_ = true;
   SetNeedsCommit();
 }
 
 }  // namespace cc