The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7821527cafe2199a3603d26daae639c621602a2f

commit 7821527cafe2199a3603d26daae639c621602a2f
Author: yuweih <yuweih@chromium.org>
Date: Thu Apr 07 17:53:48 2016

When using third-party authentication the host may need to use client certificates. The host currently doesn't handle the case that the certificate file gets updated when the host is running, in which case later session connection will fail due to outdated certificate.

This patch schedules host-restart when the cert folder (~/.pki/nssdb) is changed and restart the host when no client connection is established.

BUG= 598819 

Review URL: https://codereview.chromium.org/1838313002

Cr-Commit-Position: refs/heads/master@{#385801}

[modify] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/host/BUILD.gn
[add] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/host/linux/certificate_watcher.cc
[add] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/host/linux/certificate_watcher.h
[add] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/host/linux/certificate_watcher_unittest.cc
[modify] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/host/remoting_me2me_host.cc
[modify] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/remoting_host_srcs.gypi
[modify] https://crrev.com/7821527cafe2199a3603d26daae639c621602a2f/remoting/remoting_test.gypi