Support changing Google Account identity strings

If auth.allowGoogleAccountUpgrade is set to true we now allow the
user's OpenID identity token to change during sign-in, such as if
the server hostname was recently changed.

Change-Id: I5d88ce8d39186ef22fd47b257a3c791c2b2c12bd
Signed-off-by: Shawn O. Pearce <sop@google.com>
2 files changed