Hit test on the layer tree rather than the RSLL

cc/layers/draw_properties.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_DRAW_PROPERTIES_H_
 #define CC_LAYERS_DRAW_PROPERTIES_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
@@ skipping 13 matching lines @@
         can_use_lcd_text(false),
         is_clipped(false),
         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),
         has_child_with_a_scroll_parent(false),
         sorted_for_recursion(false),
+        is_in_layer_list(false),
         index_of_first_descendants_addition(0),
         num_descendants_added(0),
         index_of_first_render_surface_layer_list_addition(0),
         num_render_surfaces_added(0) {}
 
   // Transforms objects from content space to target surface space, where
   // this layer would be drawn.
   gfx::Transform target_space_transform;
 
   // Transforms objects from content space to screen space (viewport space).
@@ skipping 60 matching lines @@
   // This is true if the layer has any direct child that has a scroll parent.
   // This layer will not be the scroll parent in this case. This information
   // lets us avoid work in CalculateDrawPropertiesInternal -- if none of our
   // children have scroll parents, we will not need to recur out of order.
   bool has_child_with_a_scroll_parent;
 
   // This is true if the order (wrt to its siblings in the tree) in which the
   // layer will be visited while computing draw properties has been determined.
   bool sorted_for_recursion;
 
+  // This returns true if the layer has been included in some surface's layer
+  // list (i.e., this thing will draw).
+  bool is_in_layer_list;

[enne (OOO), 2014/05/06 20:30:58]

vmpstr is doing something like this as well in
https://codereview.chromium.org/265883013/

[Ian Vollick, 2014/05/06 21:06:20]

As we discussed offline, this is subsumed by vmpstr's patch, so I'll wait for
his to land. I'll upload a rebase against that patch as soon as I can.

+
   // If this layer is visited out of order, its contribution to the descendant
   // and render surface layer lists will be put aside in a temporary list.
   // These values will allow for an efficient reordering of these additions.
   size_t index_of_first_descendants_addition;
   size_t num_descendants_added;
   size_t index_of_first_render_surface_layer_list_addition;
   size_t num_render_surfaces_added;
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_