Revert of cc: Change TileManager iterators to be queues.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 4ff86e002671d969ef73fa7d4adefd9269504dbf..4a7e0c0b0b66ae5bdf20743b65c0f51c69824c0d 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -45,17 +45,6 @@
 }  // namespace
 
 namespace cc {
-
-PictureLayerImpl::Pair::Pair() : active(NULL), pending(NULL) {
-}
-
-PictureLayerImpl::Pair::Pair(PictureLayerImpl* active_layer,
-                             PictureLayerImpl* pending_layer)
-    : active(active_layer), pending(pending_layer) {
-}
-
-PictureLayerImpl::Pair::~Pair() {
-}
 
 PictureLayerImpl::PictureLayerImpl(LayerTreeImpl* tree_impl, int id)
     : LayerImpl(tree_impl, id),