Baseline: 9a765c8b498a72e20af6c391bef01e794913c317

Cherry picks:

   + f959a22bc59229b723cfca8c987da210b03b8a8d:
     Rollback.

Important changes:

  - Add support to length-delimited protos as undeclared output
    annotations []

This release contains contributions from many people at Google, as well as Benjamin Peterson, Brandon Jacklyn, Rabi Shanker Guha.