code: func (p *printer) commit(c *pb.GitilesCommit) {
  	if c.Id == "" {
  		p.linkf("https://%s/%s/+/%s", c.Host, c.Project, c.Ref)
  		return
  	}
  
  	switch c.Host {
  	// This shamelessly hardcodes https://cr-rev.appspot.com/_ah/api/crrev/v1/projects response
  	// TODO(nodir): make an RPC and cache on the file system.
  	case
  		"aomedia.googlesource.com",
  		"boringssl.googlesource.com",
  		"chromium.googlesource.com",
  		"gerrit.googlesource.com",
  		"webrtc.googlesource.com":
  		p.linkf("https://crrev.com/" + c.Id)
  	default:
  		p.linkf("https://%s/%s/+/%s", c.Host, c.Project, c.Id)
  	}
  	if c.Ref != "" {
  		p.f(" on %s", c.Ref)
  	}
  }
docs: // commit prints c.