Baseline: 7fb50baaa00f92c6f009dcf1684427fc8fa1f301

Cherry picks:

   + 0ebf7bc8376f8ca9e865b81658c2f2b29aaf7f4d:
     Automated rollback of commit
     1acc7a843bf0996c26a1e3d74bb64514395b7e7f.

Incompatible changes:

  - Renamed PackageMetrics proto message to PackageLoadMetrics. The
    formats should be wire compatible.

This release contains contributions from many people at Google, as well as Ankit Agarwal, Benjamin Peterson, Fabian Meumertzheim, Jasper, Son Luong Ngoc, Xdng Yng.