am 2b5aa3e3: merge in release branch changes (no-op).

* commit '2b5aa3e38b55f28ea1c5f619b921a7470cc926a0':
  Add GCam progress indicator.
  hide preview cover on arrival of new preview data if hidden
  Fix photo mode is getting stuck in a single CameraState.
  Show chooser on EDIT intents that have no activity for action.
  Parallelize opening the camera with view handling in photo mode.
  Decouple the visibility check for system UI from action bar
  Don't crash Photo Sphere on back button press in filmstrip.
  Check for media service being present before capture.