Merged LogoService and LogoTracker.

LogoTracker is now an implementation detail of LogoService.
In order to simplify things further,
its implementation was moved inside LogoService.

Bug: 761829
Change-Id: I33e5ab909e3f66aec31546bb1833069f973216c9
Reviewed-on: https://chromium-review.googlesource.com/c/1349511
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Yeol Park <peary2@gmail.com>
Cr-Commit-Position: refs/heads/master@{#614651}
8 files changed