Remove crash on retail mode startup.

This CHECK was originally added because retail mode was supposed to not be supported anymore in R38:
https://chromium.googlesource.com/chromium/src.git/+/0dfff001d347879953bbeaa4e128c24e4e9fcc94

Since too many crashes were reported for R38, this removes the CHECK to support retail mode again.

BUG=422095
TEST=Ran retail mode in R38 and verified that it correctly logs in.

Review URL: https://codereview.chromium.org/651843002

Cr-Commit-Position: refs/heads/master@{#299293}

chromeos/login/login_state.cc

@@ -68,7 +68,6 @@ void LoginState::SetLoggedInStateAndPrimaryUser(
 }
 
 void LoginState::SetLoggedInState(LoggedInState state, LoggedInUserType type) {
-  CHECK_NE(LOGGED_IN_USER_RETAIL_MODE, type);
   if (state == logged_in_state_ && type == logged_in_user_type_)
     return;
   VLOG(1) << "LoggedInState: " << state << " UserType: " << type;
@@ -97,7 +96,8 @@ bool LoginState::IsGuestSessionUser() const {
 }
 
 bool LoginState::IsPublicSessionUser() const {
-  return logged_in_user_type_ == LOGGED_IN_USER_PUBLIC_ACCOUNT;
+  return logged_in_user_type_ == LOGGED_IN_USER_PUBLIC_ACCOUNT ||
+         logged_in_user_type_ == LOGGED_IN_USER_RETAIL_MODE;
 }
 
 bool LoginState::IsKioskApp() const {