am 999d483b: am 49a8bbf4: Don\'t crash if we\'ve never gotten a signal strength update.

Merge commit '999d483bf8fc4271c42484aaf253f12e4eb8ff29'

* commit '999d483bf8fc4271c42484aaf253f12e4eb8ff29':
  Don't crash if we've never gotten a signal strength update.