am f51f24a6: Use the new sdk/build/tools.atree.

Merge commit 'f51f24a6ea5d972dcaf60f882c26a0a08c9014fc' into gingerbread-plus-aosp

* commit 'f51f24a6ea5d972dcaf60f882c26a0a08c9014fc':
  Use the new sdk/build/tools.atree.