Convert //cc from scoped_ptr to std::unique_ptr.

cc/layers/picture_image_layer_impl.cc

Index: cc/layers/picture_image_layer_impl.cc
diff --git a/cc/layers/picture_image_layer_impl.cc b/cc/layers/picture_image_layer_impl.cc
index c816986d6a1df6b15f5c11a030077229769af845..eeae33c367aa77f83bd744316227396dab22828d 100644
--- a/cc/layers/picture_image_layer_impl.cc
+++ b/cc/layers/picture_image_layer_impl.cc
@@ -23,7 +23,7 @@ const char* PictureImageLayerImpl::LayerTypeAsString() const {
   return "cc::PictureImageLayerImpl";
 }
 
-scoped_ptr<LayerImpl> PictureImageLayerImpl::CreateLayerImpl(
+std::unique_ptr<LayerImpl> PictureImageLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return PictureImageLayerImpl::Create(tree_impl, id(), is_mask_);
 }