cc: Give non-drawing layers that are rasterized a lower priority.

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 f43c977f6846f5e1cacb58731f69821164c62a34..328d7e9bd9218186e7a009ef8ebd8fe484ebec6d 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -515,7 +515,9 @@ bool PictureLayerImpl::UpdateTiles() {
   // The reason for this is that we should be able to activate sooner and get a
   // more up to date recording, so we don't run out of recording on the active
   // tree.
-  bool can_require_tiles_for_activation =
+  // A layer must be a drawing layer for it to require tiles for activation.
+  bool can_require_tiles_for_activation = contributes_to_drawn_render_surface();

[Khushal, 2017/05/24 21:57:06]

Should this be done for requiring tiles for draw as well? I'm guessing there
wouldn't be much impact in the renderer from that right now since we don't block
drawing on ReadyToDraw there.

+  can_require_tiles_for_activation &=
       !only_used_low_res_last_append_quads_ || RequiresHighResToDraw() ||
       !layer_tree_impl()->SmoothnessTakesPriority();