Changes subtreeShouldRenderToSeparateSurface logic to account for explicit clipping

ui/gfx/transform.h

Index: ui/gfx/transform.h
diff --git a/ui/gfx/transform.h b/ui/gfx/transform.h
index 2be72efd0d7bf91c51409f574ac37f52a9820297..6e69c9df400ce89830f96393ef915dee4da15f0c 100644
--- a/ui/gfx/transform.h
+++ b/ui/gfx/transform.h
@@ -78,6 +78,15 @@ class UI_EXPORT Transform {
     return !(matrix_.getType() & ~SkMatrix44::kTranslate_Mask);
   }
 
+  // Returns trus if the matrix is either a scale and/or translation
+  bool IsPositiveScaleOrTranslation() const {

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

I would like to keep unit testing on gfx::transform very draconian and
comprehensive.  So we need unit tests that cover positive, negative, and zero
scales for x, y, and z.  If you want to defer making this unit test to a
follow-up patch, make sure that's ok with danakj first and let's create a crbug
assigned to one of us so that we do not forget it.

[whunt, 2012/12/18 19:48:15]

Assigning crbug to Shawn.

On 2012/12/18 19:11:00, shawnsingh wrote:

+    if (!IsScaleOrTranslation())
+      return false;
+    return matrix_.getDouble(0, 0) > 0.0 &&
+        matrix_.getDouble(1, 1) > 0.0 &&
+        matrix_.getDouble(2, 2) > 0.0;
+  }
+
   // Returns true if the matrix is either identity or pure, non-fractional
   // translation.
   bool IsIdentityOrIntegerTranslation() const;