Keeping track of descendants that draw content instead of recalcualting

cc/layers/draw_properties.h

Index: cc/layers/draw_properties.h
diff --git a/cc/layers/draw_properties.h b/cc/layers/draw_properties.h
index a0bfc2a6f2f741eedb036e5c73d8c5c10baeaa27..4bbce727deff70f122c131dad21a4b756a01d72c 100644
--- a/cc/layers/draw_properties.h
+++ b/cc/layers/draw_properties.h
@@ -26,7 +26,6 @@ struct CC_EXPORT DrawProperties {
         render_target(NULL),
         contents_scale_x(1.f),
         contents_scale_y(1.f),
-        num_descendants_that_draw_content(0),
         num_unclipped_descendants(0),
         layer_or_descendant_has_copy_request(false),
         layer_or_descendant_has_input_handler(false),
@@ -96,9 +95,6 @@ struct CC_EXPORT DrawProperties {
   float contents_scale_y;
   gfx::Size content_bounds;
 
-  // Does not include this layer itself, only its children and descendants.
-  int num_descendants_that_draw_content;
-
   // Number of descendants with a clip parent that is our ancestor. NB - this
   // does not include our clip children because they are clipped by us.
   int num_unclipped_descendants;