am 49a8bbf4: Don\'t crash if we\'ve never gotten a signal strength update.

Merge commit '49a8bbf4eacbf0bde71bab05be0ab40488df109c' into gingerbread-plus-aosp

* commit '49a8bbf4eacbf0bde71bab05be0ab40488df109c':
  Don't crash if we've never gotten a signal strength update.