GitLab

This CL removes AccountTrackerService from IdentityAPI and
uses IdentityManager instead of it.

Bug: 922750, 922751
Change-Id: Ibb4f2cd90fd9439b0889f25608d8491d110dcba0
Reviewed-on: https://chromium-review.googlesource.com/c/1429883Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#625434}