Minimize state changes when updating layers

Change-Id: I407fcc80bd3178f9f09a3b379ceb7f7ce0749e08
diff --git a/libs/hwui/LayerRenderer.h b/libs/hwui/LayerRenderer.h
index 531aa5b..8d42f7f 100644
--- a/libs/hwui/LayerRenderer.h
+++ b/libs/hwui/LayerRenderer.h
@@ -47,6 +47,7 @@
     ANDROID_API LayerRenderer(Layer* layer);
     virtual ~LayerRenderer();
 
+    virtual void setViewport(int width, int height);
     virtual int prepareDirty(float left, float top, float right, float bottom, bool opaque);
     virtual void finish();