Improve Aura overdraw by changing hole calculation

ui/gfx/transform.h

Index: ui/gfx/transform.h
diff --git a/ui/gfx/transform.h b/ui/gfx/transform.h
index 483aa564652c9cf47d2b0ae49d475406a3a9a596..0887f51259987b3935abbec7658d0efa95a2722a 100644
--- a/ui/gfx/transform.h
+++ b/ui/gfx/transform.h
@@ -69,6 +69,9 @@ class UI_EXPORT Transform {
   // Does the transformation change anything?
   bool HasChange() const;
 
+  // Inverts the transform. Returns true if successful;
+  bool Invert();
+
   // Applies the transformation on the point. Returns true if the point is
   // transformed successfully.
   void TransformPoint(gfx::Point3f& point) const;