cc: Move SyncedScrollOffset to scroll tree

cc/trees/layer_tree_impl.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 111 matching lines @@
   void GetAllPrioritizedTilesForTracing(
       std::vector<PrioritizedTile>* prioritized_tiles) const;
   void AsValueInto(base::trace_event::TracedValue* dict) const;
 
   // Other public methods
   // ---------------------------------------------------------------------------
   LayerImpl* root_layer() const { return root_layer_.get(); }
   void SetRootLayer(scoped_ptr<LayerImpl>);
   scoped_ptr<LayerImpl> DetachLayerTree();
 
-  void SetPropertyTrees(const PropertyTrees& property_trees) {
+  void SetPropertyTrees(const PropertyTrees property_trees) {
     property_trees_ = property_trees;
+    property_trees_.is_main_thread = false;
+    property_trees_.is_active = IsActiveTree();
     property_trees_.transform_tree.set_source_to_parent_updates_allowed(false);
   }
   PropertyTrees* property_trees() { return &property_trees_; }
 
   void UpdatePropertyTreesForBoundsDelta();
 
   void PushPropertiesTo(LayerTreeImpl* tree_impl);
 
   int source_frame_number() const { return source_frame_number_; }
   void set_source_frame_number(int frame_number) {
@@ skipping 40 matching lines @@
   void set_background_color(SkColor color) { background_color_ = color; }
 
   bool has_transparent_background() const {
     return has_transparent_background_;
   }
   void set_has_transparent_background(bool transparent) {
     has_transparent_background_ = transparent;
   }
 
   void UpdatePropertyTreeScrollingAndAnimationFromMainThread();
+  void UpdatePropertyTreeScrollOffset(PropertyTrees* property_trees) {
+    if (root_layer())
+      property_trees_.scroll_tree.UpdateScrollOffsetMap(
+          &property_trees->scroll_tree.scroll_offset_map(),
+          root_layer()->layer_list_impl());

[ajuma, 2016/03/01 22:54:20]

Can this use layer_list_ directly (without going through root_layer() or
depending on the existence of root_layer())?

[sunxd, 2016/03/02 17:45:34]

Since the layer_list change is reverted. I can keep using layer_tree_impl here.
So the problem is resolved currently.

+  }
   void SetPageScaleOnActiveTree(float active_page_scale);
   void PushPageScaleFromMainThread(float page_scale_factor,
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
   float current_page_scale_factor() const {
     return page_scale_factor()->Current(IsActiveTree());
   }
   float min_page_scale_factor() const { return min_page_scale_factor_; }
   float max_page_scale_factor() const { return max_page_scale_factor_; }
 
@@ skipping 332 matching lines @@
   // the layer tree.
   scoped_ptr<LayerListImpl> layer_list_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_