Add IsAuthenticated() method to SigninManager.

chrome/browser/sync/supervised_user_signin_manager_wrapper.cc

Index: chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
diff --git a/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc b/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
index 9abdc9a0cacf2a2379458f629ae71b64c0cfab0a..21b045ed000c636b7f2ca78e8653cffc563516af 100644
--- a/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
+++ b/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
@@ -34,18 +34,16 @@ std::string SupervisedUserSigninManagerWrapper::GetEffectiveUsername() const {
 }
 
 std::string SupervisedUserSigninManagerWrapper::GetAccountIdToUse() const {
-  const std::string& auth_account = original_->GetAuthenticatedAccountId();
 #if defined(ENABLE_MANAGED_USERS)
-  if (auth_account.empty() && profile_->IsSupervised())
+  if (!original_->IsAuthenticated() && profile_->IsSupervised())
     return supervised_users::kSupervisedUserPseudoEmail;
 #endif
-  return auth_account;
+  return original_->GetAuthenticatedAccountId();
 }
 
 std::string SupervisedUserSigninManagerWrapper::GetSyncScopeToUse() const {
 #if defined(ENABLE_MANAGED_USERS)
-  const std::string& auth_account = original_->GetAuthenticatedAccountId();
-  if (auth_account.empty() && profile_->IsSupervised())
+  if (!original_->IsAuthenticated() && profile_->IsSupervised())
     return GaiaConstants::kChromeSyncSupervisedOAuth2Scope;
 #endif
   return GaiaConstants::kChromeSyncOAuth2Scope;