cc: Fix hit-testing in zero-opacity layers.

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 16 matching lines @@
         contents_scale_x(1.f),
         contents_scale_y(1.f),
         num_descendants_that_draw_content(0),
         num_unclipped_descendants(0),
         can_draw_directly_to_backbuffer(false),
         layer_or_descendant_has_copy_request(false),
         sorted_for_recursion(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) {}
+        num_render_surfaces_added(0),
+        layer_or_descendant_has_event_handler(false) {}
 
   // 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).
   gfx::Transform screen_space_transform;
 
   // DrawProperties::opacity may be different than LayerType::opacity,
   // particularly in the case when a RenderSurface re-parents the layer's
@@ skipping 59 matching lines @@
   // layer will be visited while computing draw properties has been determined.
   bool sorted_for_recursion;
 
   // 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;
+
+  // If true, the layer or some layer in its sub-tree has mousewheel or touch
+  // event handlers,
+  bool layer_or_descendant_has_event_handler;
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_