Don't clear the framebuffer when not needed.
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index e3d4653..4caa8fb 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -67,7 +67,7 @@
 
     virtual void setViewport(int width, int height);
 
-    virtual void prepare();
+    virtual void prepare(bool opaque);
     virtual void finish();
 
     virtual void acquireContext();