am cdd44a0d: added a new hint to tell SF it should clear the FB for some layers

Merge commit 'cdd44a0db36749af5036e903e4867b279ef420df' into gingerbread-plus-aosp

* commit 'cdd44a0db36749af5036e903e4867b279ef420df':
  added a new hint to tell SF it should clear the FB for some layers