GitLab

It's replaced by base::ScopedObservation for observing a single source,
or base::ScopedMultiSourceObservation for observing multiple sources.

Bug: 1145565
Change-Id: Iadc2e3efee7860e1b17b86b077d4c6a2566b6a95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527541
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825580}