Draw in the correct FBO after invoking a GL functor
Bug #5650514

After invoking a GL functor, libhwui restores a few OpenGL states
including the current FBO. The renderer was however making the
wrong assumption that the FBO to restore to was the base layer
instead of the FBO associated with the current canvas state.

Change-Id: Ie565500832ebffd673f6a43b83422d6cc05470a0
diff --git a/libs/hwui/Snapshot.h b/libs/hwui/Snapshot.h
index d51154d..aff7b93 100644
--- a/libs/hwui/Snapshot.h
+++ b/libs/hwui/Snapshot.h
@@ -213,7 +213,8 @@
     Layer* layer;
 
     /**
-     * Only set when the flag kFlagIsFboLayer is set.
+     * Target FBO used for rendering. Set to 0 when rendering directly
+     * into the framebuffer.
      */
     GLuint fbo;