Update comment making reference to an old file.
Update comment making reference to an old file.

The monitor layout is described in monitor.cc. A comment was making reference
to a non exisitng Sync.c file. This CL updates this comment.

Change-Id: I1b3523827dc081b15d077ac50af601a72ed52d5d

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst