cc: Remove some unnecessary const scoped_refptr&.

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 <unordered_map>
 
 #include "base/macros.h"
@@ skipping 48 matching lines @@
  private:
   LayerProtoConverter();
   ~LayerProtoConverter();
 
   // This method is the inner recursive function for SerializeLayerProperties
   // declared above.
   static void RecursivelySerializeLayerProperties(
       Layer* root_layer,
       proto::LayerUpdate* layer_update);
 
   using LayerIdMap = std::unordered_map<int, scoped_refptr<Layer>>;

[danakj, 2016/03/16 00:08:15]

Does this need to be refptrs? If so the FindAllLayers may as well take a refptr,
cuz it's going to turn the raw pointer back into one.

[vmpstr, 2016/03/16 16:38:37]

I think it makes sense for the map to be owning, since that's where the layer
children / masks are taken from when they exist. Those things are ref counted.
In other words, even if this map has raw pointers we'll still be creating ref
counted objects out of them and I would prefer to then have ref counting as
early as possible. 

The function itself though begins iteration with a raw pointer, hence this
change. I've added a TODO here to fix it better.

[danakj, 2016/03/16 18:04:31]

OK.

BTW if blink no longer changes cc during painting, we don't need to refcount
cc::Layer anymore. I thot we turned on strict property checking to verify blink
isn't doing this, maybe that bounced, enne would know where that's at.

-  // 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,
+  // Start at |root_layer| and recursively add the layer and all its children
+  // and special layers to |layer_id_map|.
+  static void RecursivelyFindAllLayers(Layer* root_layer,
                                        LayerIdMap* layer_id_map);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_PROTO_CONVERTER_H_