cc: Simplify picture layer tiling update tile priorities.

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 6c06254e0b2a2f7804b2218fbf579a2ea782ba48..1aa48ccf88933726b1930abb6bd607ab0d342fb6 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -60,6 +60,7 @@ class CC_EXPORT LayerTreeSettings {
   bool use_pinch_zoom_scrollbars;
   bool use_pinch_virtual_viewport;
   size_t max_tiles_for_interest_area;
+  float skewport_target_time_in_seconds;
   size_t max_unused_resource_memory_percentage;
   int highp_threshold_min;
   bool strict_layer_property_change_checking;