Add pid->handle mapping code to generate_dump. This is enough to get
generate_dump to start capturing a dump for an arbitrary system process.
It currently CHECK()s in ProcessSnapshotFuchsia on some unimplemented
functionality.
Bug: crashpad:196
Change-Id: Idfbaa4fbf32af63ad6db5b0b78a7a1991b82728e
Reviewed-on: https://chromium-review.googlesource.com/1005804
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>
