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

cc/layers/layer_proto_converter.cc

Index: cc/layers/layer_proto_converter.cc
diff --git a/cc/layers/layer_proto_converter.cc b/cc/layers/layer_proto_converter.cc
index 2dcc3d90a441209006cffd8f9fc55a3fc6bd4610..970c446577c28cc161cfd8c5fb04c686eb8cf0c7 100644
--- a/cc/layers/layer_proto_converter.cc
+++ b/cc/layers/layer_proto_converter.cc
@@ -42,6 +42,48 @@ scoped_refptr<Layer> LayerProtoConverter::DeserializeLayerHierarchy(
 }
 
 // static
+void LayerProtoConverter::SerializeLayerProperties(
+    const scoped_refptr<Layer> root_layer,
+    proto::LayerUpdate* layer_update) {
+  RecursivelySerializeLayerProperties(root_layer, layer_update);
+}
+
+// static
+void LayerProtoConverter::DeserializeLayerProperties(
+    scoped_refptr<Layer> existing_root,

[vmpstr, 2015/11/18 04:05:25]

Can you pass a raw pointer here instead?

[nyquist, 2015/11/18 07:15:59]

Done.

+    const proto::LayerUpdate& layer_update) {
+  LayerIdMap layer_id_map;
+  RecursivelyFindAllLayers(existing_root, &layer_id_map);
+
+  for (int i = 0; i < layer_update.layers_size(); ++i) {
+    const proto::LayerProperties& layer_properties = layer_update.layers(i);
+
+    Layer::LayerIdMap::const_iterator iter =
+        layer_id_map.find(layer_properties.id());
+    DCHECK(iter != layer_id_map.end());
+
+    iter->second->FromLayerPropertiesProto(layer_properties);
+  }
+}
+
+// static
+void LayerProtoConverter::RecursivelySerializeLayerProperties(
+    const scoped_refptr<Layer> layer,
+    proto::LayerUpdate* layer_update) {
+  bool serialize_descendants = layer->ToLayerPropertiesProto(layer_update);
+  if (!serialize_descendants)

[vmpstr, 2015/11/18 04:05:25]

Are mask/replica considered descendants? That is, do you need to serialize
mask/replica even if this returns false?

[nyquist, 2015/11/18 07:15:59]

According to Layer::SetMaskLayer(...) (
https://chromium.googlesource.com/chromium/src/+/cc1c0830a3ad08c3e1c346fdf23a...
) and Layer::SetReplicaLayer(...) (
https://chromium.googlesource.com/chromium/src/+/cc1c0830a3ad08c3e1c346fdf23a...
) both the mask and replica layer gets the current layer as their parent, which
from what I can tell means that SetNeedsPushProperties will traverse up the
tree.

So, if I've understood that correctly, there's not really a difference from mask
and replica layers versus normal children, and they will all need to be looked
at if num_dependents_need_push_properties_ > 0.

+    return;
+
+  for (const auto& child : layer->children()) {
+    RecursivelySerializeLayerProperties(child, layer_update);
+  }
+  if (layer->mask_layer())
+    RecursivelySerializeLayerProperties(layer->mask_layer(), layer_update);
+  if (layer->replica_layer())
+    RecursivelySerializeLayerProperties(layer->replica_layer(), layer_update);
+}
+
+// static
 void LayerProtoConverter::RecursivelyFindAllLayers(
     const scoped_refptr<Layer>& layer,
     LayerIdMap* layer_id_map) {