Remove GaiaCookieManagerService dependency from ChildAccountService

ChildAccountService was observing changes the list of gaia accounts in
the cookie jar in order to notify its observers. We can achieve the
same behaviour by observing IdentityManager instead.

Apart from that the call to GaiaCookieManagerService::ListAccounts()
was successfully replaced by
IdentityManager::GetAccountsInCookieJar(). This allows us to
completely remove the dependency on GaiaCookieManagerService.

Bug: 921007
Change-Id: I7acc064c65ae2d61eb9d807e08183f2ee30e5183
Reviewed-on: https://chromium-review.googlesource.com/c/1409010
Commit-Queue: Sergio Villar <svillar@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629957}
2 files changed