GitLab

It is not necessary to kill the entire process group to dump it, and it is not
required to ptrace() it. Fix the first one, and document why ptrace() may still
be useful.

Reported by bgeffon@google.com.

Bug: 845459
Change-Id: I9f08e7208cfcfdec00bcaf80f83c585f1d4ea195
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1675649Reviewed-by: Egor Pasko <pasko@chromium.org>
Commit-Queue: Benoit L <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672040}