This adds dependencies on the perfetto, protobuf, and protobuf-gn repos on fuchsia.googlesource.com.
Change-Id: Ib196587e4cacb7e95c5ca284539fcd578d09d16b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/278200
Commit-Queue: Derek Xu <derekx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
