Changes subtreeShouldRenderToSeparateSurface logic to account for explicit clipping

cc/draw_properties.h

Index: cc/draw_properties.h
diff --git a/cc/draw_properties.h b/cc/draw_properties.h
index 3895ef0720ab675044c7f7f9d63142261ac8e3ed..7015fad661623fbbd58a6702e932b89d058c6ece 100644
--- a/cc/draw_properties.h
+++ b/cc/draw_properties.h
@@ -25,6 +25,7 @@ struct CC_EXPORT DrawProperties {
         , is_clipped(false)
         , render_target(0)
         , num_descendants_that_draw_content(0)
+        , does_not_require_scissoring(false)
     {
     }
 
@@ -77,6 +78,10 @@ struct CC_EXPORT DrawProperties {
 
     // Does not include this layer itself, only its children and descendants.
     int num_descendants_that_draw_content;
+
+    // If true, every node in the sub-tree can clip itself without the need
+    // to use hardware sissoring or a new render target.
+    int does_not_require_scissoring;

[shawnsingh, 2012/12/18 19:11:00]

I feel like scissoring isn't the right word here.  scissoring is one method of
implementing the clip;  the other method the code currently uses is to
implicitly clip by having a renderSurface with limited bounds.   So I feel like
this variable name may get confusing.   More comments about this variable name
below.

 };
 
 }  // namespace cc