[ash-md] Adds support for Z-order iteration in views::View

ui/views/view.h

Index: ui/views/view.h
diff --git a/ui/views/view.h b/ui/views/view.h
index a6811afca8a5c084b0d81d5ab375e483cc46c006..0b51589cb3efa763b2550a217a19ac345cb226bb 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -307,6 +307,12 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   // Returns whether the view is enabled.
   bool enabled() const { return enabled_; }
 
+  // Get a container of |children_| arranged according to the stacking order.

[sky, 2016/12/13 23:40:56]

How about:
Returns the child views ordered in reverse z-order. That is, views later in the
returned vector have a higher z-order (are painted later) than those early in
the vector. The returned vector has exactly the same number of Views as
children(). The default implementation returns children(), subclass if the paint
order should differ from that of children().

I'm also wondering if it should be named GetChildrenOrderedByZOrder()? But I'm
ok with what you have.

Can this be protected?

[varkha, 2016/12/14 17:51:38]

I will look into the rest of the comments but making it protected would require
friending ViewTargeterDelegate::TargetForRect, no?

[varkha, 2016/12/19 20:35:44]

Done (edited the comment).

+  // This defaults to returning |children_| but can be overridden to implement
+  // a different stacking order. This order is taken into account by painting
+  // and targeting implementations.
+  virtual View::Views GetChildrenOrderedByVisualOrder();
+
   // Transformations -----------------------------------------------------------
 
   // Methods for setting transformations for a view (e.g. rotation, scaling).