cc: Move SyncedScrollOffset to scroll tree

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 <unordered_map>
 #include <vector>
 
 #include "cc/base/cc_export.h"
+#include "cc/base/synced_property.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 namespace proto {
 class ClipNodeData;
 class EffectNodeData;
 class PropertyTree;
 class PropertyTrees;
 class ScrollNodeData;
 class TranformNodeData;
 class TransformTreeData;
 class TreeNode;
 }
 
+class LayerListImpl;
+struct ScrollAndScaleSet;
+
 // ------------------------------*IMPORTANT*---------------------------------
 // Each class declared here has a corresponding proto defined in
 // cc/proto/property_tree.proto. When making any changes to a class structure
 // including addition/deletion/updation of a field, please also make the
 // change to its proto and the ToProtobuf and FromProtobuf methods for that
 // class.
 
+typedef SyncedProperty<AdditionGroup<gfx::ScrollOffset>> SyncedScrollOffset;

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

This typedef also exists in layer_impl.h. Can it go into a common place?

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

Done.

+
 template <typename T>
 struct CC_EXPORT TreeNode {
   TreeNode() : id(-1), parent_id(-1), owner_id(-1), data() {}
   int id;
   int parent_id;
   int owner_id;
   T data;
 
   bool operator==(const TreeNode<T>& other) const;
 
@@ skipping 495 matching lines @@
  private:
   void UpdateOpacities(EffectNode* node, EffectNode* parent_node);
   void UpdateIsDrawn(EffectNode* node, EffectNode* parent_node);
 };
 
 class CC_EXPORT ScrollTree final : public PropertyTree<ScrollNode> {
  public:
   ScrollTree();
   ~ScrollTree() override;
 
+  ScrollTree& operator=(const ScrollTree& from);
   bool operator==(const ScrollTree& other) const;
 
   void ToProtobuf(proto::PropertyTree* proto) const;
   void FromProtobuf(const proto::PropertyTree& proto);
 
+  void clear() override;
+
+  typedef std::unordered_map<int, scoped_refptr<SyncedScrollOffset>>
+      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;
 
+  // synced_scroll_offset is supposed to be called by Layer/LayerImpl only

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

Would things break if something else called this?

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

It would not. This is only a logical restriction. Once the scroll offset is
passed from main thread to impl thread, only layers can modify the deltas.

I also make scroll tree itself call this function.

[ajuma, 2016/03/02 18:43:09]

Should this be a TODO then? (about removing this)

[sunxd, 2016/03/02 20:52:55]

Done.

[sunxd, 2016/03/02 20:52:55]

I think the prerequisite is that layer/layer_impl no longer manipulates
scroll_offset. I'll add it here.

+  SyncedScrollOffset* synced_scroll_offset(int layer_id);
+  void CollectScrollDeltas(ScrollAndScaleSet* scroll_info);
+  void UpdateScrollOffsetMapEntry(int key,
+                                  ScrollOffsetMap* new_scroll_offset_map,
+                                  LayerListImpl* layer_list_impl);
+  void UpdateScrollOffsetMap(ScrollOffsetMap* new_scroll_offset_map,
+                             LayerListImpl* layer_list_impl);
+  ScrollOffsetMap& scroll_offset_map();
+  const ScrollOffsetMap& scroll_offset_map() const;
+  void ApplySentScrollDeltasFromAbortedCommit();
+
  private:
   int currently_scrolling_node_id_;
+  ScrollOffsetMap layer_id_to_scroll_offset_map_;
+
+  gfx::ScrollOffset PullDeltaForMainThread(SyncedScrollOffset* scroll_offset);
 };
 
 class CC_EXPORT PropertyTrees final {
  public:
   PropertyTrees();
   ~PropertyTrees();
 
   bool operator==(const PropertyTrees& other) const;
   PropertyTrees& operator=(const PropertyTrees& from);
 
   void ToProtobuf(proto::PropertyTrees* proto) const;
   void FromProtobuf(const proto::PropertyTrees& proto);
 
   TransformTree transform_tree;
   EffectTree effect_tree;
   ClipTree clip_tree;
   ScrollTree scroll_tree;
   bool needs_rebuild;
   bool non_root_surfaces_enabled;
   // Change tracking done on property trees needs to be preserved across commits
   // (when they are not rebuild). We cache a global bool which stores whether
   // we did any change tracking so that we can skip copying the change status
   // between property trees when this bool is false.
   bool changed;
   int sequence_number;
+  bool is_main_thread;
+  bool is_active;
 
   void SetInnerViewportContainerBoundsDelta(gfx::Vector2dF bounds_delta);
   void SetOuterViewportContainerBoundsDelta(gfx::Vector2dF bounds_delta);
   void SetInnerViewportScrollBoundsDelta(gfx::Vector2dF bounds_delta);
   void PushChangeTrackingTo(PropertyTrees* tree);
 
   gfx::Vector2dF inner_viewport_container_bounds_delta() const {
     return inner_viewport_container_bounds_delta_;
   }
 
   gfx::Vector2dF outer_viewport_container_bounds_delta() const {
     return outer_viewport_container_bounds_delta_;
   }
 
   gfx::Vector2dF inner_viewport_scroll_bounds_delta() const {
     return inner_viewport_scroll_bounds_delta_;
   }
 
  private:
   gfx::Vector2dF inner_viewport_container_bounds_delta_;
   gfx::Vector2dF outer_viewport_container_bounds_delta_;
   gfx::Vector2dF inner_viewport_scroll_bounds_delta_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_