Implements InitializeException() in ProcessSnapshot, and pulls it all
together writing the dump in crash handler. Sample output at crash
00163eff624e653e on the staging server.
Also adds a child-retrieve helper to koid_utilities.
Bug: crashpad:196
Change-Id: I4bee7655e81e3243ac0ae896ff0caea7ce4acdad
Reviewed-on: https://chromium-review.googlesource.com/1044771
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Joshua Peraza <jperaza@chromium.org>