handler/mac: Forward exceptions to the system crash reporter

handler/mac: Forward exceptions to the system crash reporter.

TEST=run_with_crashpad --handler crashpad_handler \
         -a --database=/tmp/crashpad_db \
         -a --url=https://clients2.google.com/cr/staging_report \
         -a --annotation=prod=crashpad \
         -a --annotation=ver=0.7.0 \
         crashy_program

R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/b8d2129bc1c06410babb93d2704b686fc34bb93f

[Mark Mentovai, 2015-03-10 20:33:40]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2015-03-10 20:45:49]

How will we disable this for things like renderer crashes and CHROME_HEADLESS=1?

[Mark Mentovai, 2015-03-10 21:02:41]

The next change will add a method to the client interface to disable Crashpad
processing and to disable forwarding to the system crash reporter. We’ll pick
those signals up here in the handler.

[Robert Sesek, 2015-03-10 21:09:12]

LGTM

[Mark Mentovai, 2015-03-10 21:10:03]

Committed patchset #1 (id:1) manually as
b8d2129bc1c06410babb93d2704b686fc34bb93f (presubmit successful).