The window manager process (ash) caches some state about the browser
process, and the browser caches some state about ash. We eventually
want to make these processes restartable, but for now we need to
terminate the browser if ash crashes. When the browser terminates on
Chrome OS the OS-level session manager daemon will restart it.

This broke when we moved the mojo service manager back into the
browser process.

Also clean up the old ShouldTerminateServiceManagerOnInstanceQuit
support we were using for the standalone and background run modes
for service manager, since we're not using those modes right now.

Ctrl-Alt-Shift-K to crash ash, see the browser exit too

Bug: 678683, 772098
Test: unit_tests, run chrome --mash --ash-debug-shortcuts and press
Change-Id: Icc62d46b36039c12a72ba3281babd234553a3f79
Reviewed-on: https://chromium-review.googlesource.com/716930


Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508782}