Moving background animation ticking from LayerTreeHostImpl into the Scheduler.

cc/trees/layer_tree_settings.h

Index: cc/trees/layer_tree_settings.h
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 74a3b0c85bbe942c2150fbee97a490d6ab79e97a..8c11655d38d50b5be491d9836953ba06d550ce4c 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -58,6 +58,7 @@ class CC_EXPORT LayerTreeSettings {
   float top_controls_show_threshold;
   float top_controls_hide_threshold;
   double refresh_rate;
+  double background_animation_rate;
   size_t max_partial_texture_updates;
   gfx::Size default_tile_size;
   gfx::Size max_untiled_layer_size;