GitLab

This interface is intended for embedders to supply to the Signin component.
It had been created during an earlier aborted effort to componentize Signin.

BUG=332107
TBR=joi

Review URL: https://codereview.chromium.org/132083002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244139 0039d316-1c4b-4281-b951-d872f2087c98