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();

[danakj, 2017/05/25 15:49:02]

Is there a test for this?

[Khushal, 2017/05/25 22:43:22]

Done. UpdatedTilingsForNonDrawingLayers.

+  can_require_tiles_for_activation &=

[danakj, 2017/05/25 15:49:02]

while i appreciate splitting an if of || and &&s apart, this still is a long if
of || and &&s. would it read better if you instead did

if (only_used && !RequiresHighRes && SmoothnessTakesPrio)
  can_require_tiles_for_activation = false;

?

Alternatively phrase it as things that enable it, and a veto, like

bool can_require =  ... the old stuff ...;
if (!contributes_to_drawn_render_surface())
  can_require = false;

?

Alteralternatively give a name for your brain to use for a subset, like

bool some_name = ... the old stuff ...;
bool can_require = some_name && contributes_to_drawn()

?

[Khushal, 2017/05/25 22:43:22]

I flipped this one. Seemed odd to evaluate the or conditions only to reset it
later. How's this?

       !only_used_low_res_last_append_quads_ || RequiresHighResToDraw() ||
       !layer_tree_impl()->SmoothnessTakesPriority();