Fix layer shadow transform crash

bug:17180252

Change-Id: Ia648b8c98a217a3a4973917bf255d1397802cbbe
diff --git a/libs/hwui/DamageAccumulator.h b/libs/hwui/DamageAccumulator.h
index 6f0bd8c..dd3365a 100644
--- a/libs/hwui/DamageAccumulator.h
+++ b/libs/hwui/DamageAccumulator.h
@@ -50,7 +50,7 @@
     void dirty(float left, float top, float right, float bottom);
 
     // Returns the current dirty area, *NOT* transformed by pushed transforms
-    void peekAtDirty(SkRect* dest);
+    void peekAtDirty(SkRect* dest) const;
 
     void computeCurrentTransform(Matrix4* outMatrix) const;