Avoid over-damaging layer area for multidraws

bug:19608961

Change-Id: Ib7495f155da62a352e9a010a362fd40ec0acad21
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index 5850dc6..800a9f9 100755
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -535,7 +535,13 @@
     RenderState& mRenderState;
 
 private:
-    void renderGlop(const Glop& glop, bool clearLayer = true);
+    enum class GlopRenderType {
+        Standard,
+        Multi,
+        LayerClear
+    };
+
+    void renderGlop(const Glop& glop, GlopRenderType type = GlopRenderType::Standard);
 
     /**
      * Discards the content of the framebuffer if supported by the driver.