Update progress before running the hook.
Update progress before running the hook.

This will let progress show the name of the hook while it's running.

Change-Id: I14ef2a9b5fd2bc4d8d778f5402f78a5827ffbb08
Reviewed-on: https://chromium-review.googlesource.com/731469
Reviewed-by: Dirk Pranke <6693ee08b084bb2ffa767f664c99b689395e0e4b@chromium.org>
Reviewed-by: Nico Weber <c0f02d98506190746d1cdcb01be0f37b51e27077@chromium.org>
Commit-Queue: Daniel Cheng <16123c1b20e8652874389dd38d18c4766d539508@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools