Made layout viewport scroll updates from compositor work like ordinary layers.

cc/trees/property_tree.h

 // Copyright 2014 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.
 
 #ifndef CC_TREES_PROPERTY_TREE_H_
 #define CC_TREES_PROPERTY_TREE_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 381 matching lines @@
       ScrollOffsetMap;
 
   gfx::ScrollOffset MaxScrollOffset(int scroll_node_id) const;
   gfx::Size scroll_clip_layer_bounds(int scroll_node_id) const;
   ScrollNode* CurrentlyScrollingNode();
   const ScrollNode* CurrentlyScrollingNode() const;
   void set_currently_scrolling_node(int scroll_node_id);
   gfx::Transform ScreenSpaceTransform(int scroll_node_id) const;
 
   const gfx::ScrollOffset current_scroll_offset(int layer_id) const;
-  void CollectScrollDeltas(ScrollAndScaleSet* scroll_info);
+  void CollectScrollDeltas(ScrollAndScaleSet* scroll_info,
+                           int inner_viewport_layer_id);
   void UpdateScrollOffsetMap(ScrollOffsetMap* new_scroll_offset_map,
                              LayerTreeImpl* layer_tree_impl);
   ScrollOffsetMap& scroll_offset_map();
   const ScrollOffsetMap& scroll_offset_map() const;
   void ApplySentScrollDeltasFromAbortedCommit();
   bool SetBaseScrollOffset(int layer_id,
                            const gfx::ScrollOffset& scroll_offset);
   bool SetScrollOffset(int layer_id, const gfx::ScrollOffset& scroll_offset);
   void SetScrollOffsetClobberActiveValue(int layer_id) {
     synced_scroll_offset(layer_id)->set_clobber_active_value();
@@ skipping 155 matching lines @@
   gfx::Vector2dF inner_viewport_container_bounds_delta_;
   gfx::Vector2dF outer_viewport_container_bounds_delta_;
   gfx::Vector2dF inner_viewport_scroll_bounds_delta_;
 
   PropertyTreesCachedData cached_data_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_