Get rid of link_ptr usage in BackgroundModeManager.

BUG=556939

Change-Id: I96e2fc6f76cfb85e9dac760ab77e93b9a6a7a10e
Reviewed-on: https://chromium-review.googlesource.com/1053274
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Drew Wilson <atwilson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569449}
2 files changed