Always use libappindicator if available

This is in effect a temporary fix to always use libappindicator (when
available, but we have deb/rpm dependency on the lib, so it should
always be available), whilst I fix the dependency issue we have on the
build bots which would allow me to add a hard dependency and clean up
the code.

Bug: 799144, 797332 , 419673
Change-Id: Id64a452029b00ec8d86f0d35d319bebcfd8bf99e
Reviewed-on: https://chromium-review.googlesource.com/939732
Reviewed-by: Thomas Anderson <[email protected]>
Commit-Queue: Tim Brown <[email protected]>
Cr-Commit-Position: refs/heads/master@{#539852}
1 file changed