[Background Sync] Remove unnecessary logging.

This removes some unused logging, per guidelines here:
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md#logging

Bug: 932591
Change-Id: I6f99412b7834716e5a13ab6f83c80bd09f2967ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1528536
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Auto-Submit: Mugdha Lakhani <nator@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642021}
1 file changed