Add support for (de)serializing cc::Layer properties.

cc/layers/layer_proto_converter.h

 // Copyright 2015 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_LAYERS_LAYER_PROTO_CONVERTER_H_
 #define CC_LAYERS_LAYER_PROTO_CONVERTER_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
 
 namespace cc {
 
 namespace proto {
 class LayerNode;
+class LayerUpdate;
 }
 
 // A class to faciliate (de)serialization of a Layer tree to protocol buffers.
 class CC_EXPORT LayerProtoConverter {
  public:
   // Starting at |root_layer|, serializes the layer hierarchy into the
   // proto::LayerNode.
   static void SerializeLayerHierarchy(const scoped_refptr<Layer> root_layer,
                                       proto::LayerNode* root_node);
 
   // Recursively iterate over the given LayerNode proto and read the structure
   // into a local Layer structure, re-using existing Layers. returns the new
   // root Layer after updating the hierarchy (may be the same as
   // |existing_root|).
   static scoped_refptr<Layer> DeserializeLayerHierarchy(
       scoped_refptr<Layer> existing_root,
       const proto::LayerNode& root_node);
 
+  // Starting at |root_layer|, serializes the properties of all the dirty nodes
+  // in the Layer hierarchy. The proto::LayerUpdate will contain all nodes that
+  // either are dirty or have dirty descendants. Only nodes that are dirty will
+  // contain the list of dirty properties.
+  static void SerializeLayerProperties(const scoped_refptr<Layer> root_layer,
+                                       proto::LayerUpdate* layer_update);
+
+  // Iterate over all updated layers from the LayerUpdate, and update the
+  // local Layers.
+  static void DeserializeLayerProperties(
+      scoped_refptr<Layer> existing_root,
+      const proto::LayerUpdate& layer_update);
+
   // Returns the Layer with proto.id() as the Layer id, if it exists in
   // |layer_id_map|. Otherwise, a new Layer is constructed of the type given
   // from proto.type().
   static scoped_refptr<Layer> FindOrAllocateAndConstruct(
       const proto::LayerNode& proto,
       const Layer::LayerIdMap& layer_id_map);
 
  private:
   LayerProtoConverter();
   ~LayerProtoConverter();
 
   using LayerIdMap = base::hash_map<int, scoped_refptr<Layer>>;
   // Start at |layer| and recursively add |layer| and all its children and
   // special layers to |layer_id_map|.
   static void RecursivelyFindAllLayers(const scoped_refptr<Layer>& layer,
                                        LayerIdMap* layer_id_map);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_PROTO_CONVERTER_H_