First Implementation of Snapped Points

cc/layers/layer_impl.cc

 // Copyright 2012 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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 319 matching lines @@
   layer->needs_show_scrollbars_ = needs_show_scrollbars_;
 
   if (layer_property_changed_) {
     layer->layer_tree_impl()->set_needs_update_draw_properties();
     layer->layer_property_changed_ = true;
   }
 
   layer->SetBounds(bounds_);
   layer->SetScrollClipLayer(scroll_clip_layer_id_);
   layer->SetMutableProperties(mutable_properties_);
+  layer->SetScrollSnapOffsets(snap_offsets_);
 
   // If the main thread commits multiple times before the impl thread actually
   // draws, then damage tracking will become incorrect if we simply clobber the
   // update_rect here. The LayerImpl's update_rect needs to accumulate (i.e.
   // union) any update changes that have occurred on the main thread.
   update_rect_.Union(layer->update_rect());
   layer->SetUpdateRect(update_rect_);
 
   if (owned_debug_info_)
     layer->SetDebugInfo(std::move(owned_debug_info_));
@@ skipping 149 matching lines @@
     return;
 
   bounds_ = bounds;
 
   // Scrollbar positions depend on scrolling bounds and scroll clip bounds.
   layer_tree_impl()->SetScrollbarGeometriesNeedUpdate();
 
   NoteLayerPropertyChanged();
 }
 
+void LayerImpl::SetScrollSnapOffsets(const SnapPointList& offsets) {
+  snap_offsets_ = offsets;
+  layer_tree_impl()->DidUpdateScrollState(id());
+
+  NoteLayerPropertyChanged();
+}
+
 void LayerImpl::SetViewportBoundsDelta(const gfx::Vector2dF& bounds_delta) {
   DCHECK(IsActive());
 
   if (bounds_delta == ViewportBoundsDelta())
     return;
 
   PropertyTrees* property_trees = GetPropertyTrees();
   switch (viewport_layer_type_) {
     case (INNER_VIEWPORT_CONTAINER):
       property_trees->SetInnerViewportContainerBoundsDelta(bounds_delta);
@@ skipping 470 matching lines @@
 
   const bool has_valid_scroll_node =
       !!GetScrollTree().Node(scroll_tree_index());
   DCHECK(has_valid_scroll_node);
 
   return has_valid_transform_node && has_valid_effect_node &&
          has_valid_clip_node && has_valid_scroll_node;
 }
 
 }  // namespace cc