cc: Remove some unnecessary const scoped_refptr&.

cc/layers/layer_proto_converter.h

Index: cc/layers/layer_proto_converter.h
diff --git a/cc/layers/layer_proto_converter.h b/cc/layers/layer_proto_converter.h
index 94afcb91f7bfd82fa29ed7849efd69bba3c5c0c3..10e5d4e7890b1a8d079ff2bd4ec3999d45b10b0d 100644
--- a/cc/layers/layer_proto_converter.h
+++ b/cc/layers/layer_proto_converter.h
@@ -67,9 +67,9 @@ class CC_EXPORT LayerProtoConverter {
       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);
 };