GitLab

Implements irt_exception.

This is enough to get breakpad start reporting minidumps on crash.

Stack overflow case handling with sigaltstack will be handled in a followup change.

BUG=356925
NOTRY=True

Review URL: https://codereview.chromium.org/230413002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266968 0039d316-1c4b-4281-b951-d872f2087c98