Compute if a layer is clipped outside CalcDrawProps

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 375d011f1cd9084172fc72c97553d52a86b1ce51..00eafaac6a64ddf4aef3b8e20bb290f710ec4e05 100644
--- a/cc/layers/draw_properties.h
+++ b/cc/layers/draw_properties.h
@@ -26,6 +26,7 @@ struct CC_EXPORT DrawProperties {
         screen_space_transform_is_animating(false),
         can_use_lcd_text(false),
         is_clipped(false),
+        is_clipped_from_property_trees(false),
         render_target(nullptr),
         num_unclipped_descendants(0),
         layer_or_descendant_has_copy_request(false),
@@ -73,6 +74,7 @@ struct CC_EXPORT DrawProperties {
 
   // True if the layer needs to be clipped by clip_rect.
   bool is_clipped;
+  bool is_clipped_from_property_trees;

[ajuma, 2015/07/07 17:58:48]

So far I think we've been adding 'from_property_trees' values directly on
Layer/LayerImpl rather than adding them to DrawProperties. Also, the setter for
this on Layer will need to SetNeedsPushProperties when this value changes.

[enne (OOO), 2015/07/07 18:25:48]

This is a bit odd to have both at this point in time where we are only doing CDP
on the main thread in unit tests.  Does is_clipped ever change on the compositor
thread?  It looks like the CHECK_EQ is expecting it not to.

Also, draw properties aren't pushed in general.  Can this be a layer property? 

I think what I'd like to see is have Layer::is_clipped set by the property tree
builder and pushed to LayerImpl::is_clipped.  If there are somehow unit tests
that are still calling main thread CDP only and are failing, then maybe just
make sure they call the property tree builder too.

How's that sound?

[jaydasika, 2015/07/07 18:35:28]

moved it from draw_properties to Layer/LayerImpl.

 
   // The layer whose coordinate space this layer draws into. This can be
   // either the same layer (draw_properties_.render_target == this) or an