Baseline: a52b1320da06c85d5aaa1ece9eb46acabd09b33f

Cherry picks:

   + eb956e8b6a7d12fe2c75d67abfd8c950b4c9508e:
     Fix NPE with `--watchfs` as startup option.

Incompatible changes:

  - Enforce the `--profile` path to be absolute.
  - Enforce the --memory_profile path to be absolute.

Important changes:

  - --run_validations defaults to true.

This release contains contributions from many people at Google, as well as Joe Lencioni.