GitLab

As of Blink r180944, Blink is no longer notifying the embedder of its
GeolocationController reference going away (as there's no need.) Follow
up and retire the notification implementation on the embedder side.

R=mvanouwerkerk@chromium.org, jochen@chromium.org
BUG=

Review URL: https://codereview.chromium.org/526123002

Cr-Commit-Position: refs/heads/master@{#292890}