GitLab

This CL converts SubscriptionManager from using
//components/signin to using the Identity Service client library.
The conversion is straightforward:

- Observer IdentityManager rather than SigninManager.
- Get info of primary account via IdentityManager rather than
SigninManager.
- Create PrimaryAccountAccessTokenFetcher via IdentityManager rather
than directly.

I tested the relevant behavior manually as follows, based on
instructions from mamir@chromium.org:

1. Enabled Breaking News Push by turning on "enable-breaking-newspush
on chrome://flags:
https://cs.chromium.org/chromium/src/chrome/browser/about_flags.cc?type=cs&q=kEnableBreakingNewsPushName&sq=package:chromium&l=2497

2. Checked the about:histograms for the feature's metrics by doing
"find in page" for "subscription". Saw no histogram entries after
visiting the NTP when signed out but *did* see histogram entries after
visiting the NTP when signed in. Metrics listed here:
https://cs.chromium.org/chromium/src/components/ntp_snippets/breaking_news/breaking_news_metrics.cc?type=cs&l=17

A followup change will convert the test to use IdentityTestEnvironment.

Bug: 798413
Change-Id: I9193d25c2793cf52fd825186cd5d875b352eb8bb
Reviewed-on: https://chromium-review.googlesource.com/888520
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534750}