Create SigninManagerDelegate java interface

This CL creates a stub for the java |SigninManagerDelegate| interface
and its android implementation |ChromeSigninManagerDelegate|. This
interface will provide SigninManager.java with the //chrome level
dependencies it currently has with the objective of componentizing
SigninManager.java.

This change and the next steps are detailed here:
https://docs.google.com/document/d/18887XeZNJ9pmoTdJducssk5_yVU2CQ3EqaRFoMqWCCk/

Bug: 963400
Change-Id: I1886d6183433b3ecc277e1d3ad1b82248bb02330
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610071
Commit-Queue: Pâris Meuleman <pmeuleman@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Auto-Submit: Pâris Meuleman <pmeuleman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662134}
5 files changed