Move StartRequest*() and Invalidate*() from O2TS to PO2TS

This CL is a part of moving access token management to
OAuth2AccessTokenManager.

It is specifically a step toward folding O2TS into PO2TS
now that O2TS is only one subclass of PO2TS.

It moves StartRequest*(), InvalidateAccessToken(),
and InvalidateTokenForMultilogin() from O2TS to PO2TS
as there is no instance which refers to O2TS and all
instances referred to O2TS take PO2TS with a precursor
CL [1].

[1] https://crrev.com/c/1699262

Bug: 967598
Change-Id: I05be40a70f2304f72cc0aca53177800f1e4074e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1695741
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676849}
5 files changed