debugd: Make sure all users can access tracing directory

For some reason, kernel 4.4, which uses tracefs, sets the default
permissions of /sys/kernel/debug/tracing to drwx------., which
breaks kernel traces in chrome://tracing, and Android tracing.

Resets the permission to what we had before tracefs (755).

BUG=b:30654017
TEST=chrome://tracing shows kernel events
TEST=CTS android.host.atrace passes

Change-Id: I82270efbc3024b5626677012bb973b8e6118d32a
Previous-Reviewed-on: https://chromium-review.googlesource.com/377181
(cherry picked from commit 274417514b73cfc87502d704958307ef9bd3f8c4)
Reviewed-on: https://chromium-review.googlesource.com/381772
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Commit-Queue: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Trybot-Ready: Nicolas Boichat <drinkcat@chromium.org>
1 file changed