Add username of account that has an auth error.

components/signin/ios/browser/profile_oauth2_token_service_ios.mm

Index: components/signin/ios/browser/profile_oauth2_token_service_ios.mm
diff --git a/components/signin/ios/browser/profile_oauth2_token_service_ios.mm b/components/signin/ios/browser/profile_oauth2_token_service_ios.mm
index fb184f8c0b0fd3c9d79e63d297e461d717557990..775b17893fab55fb5ccc47d128bf9b50000e74fe 100644
--- a/components/signin/ios/browser/profile_oauth2_token_service_ios.mm
+++ b/components/signin/ios/browser/profile_oauth2_token_service_ios.mm
@@ -208,6 +208,12 @@ std::string ProfileOAuth2TokenServiceIOS::AccountInfo::GetAccountId() const {
   return account_id_;
 }
 
+std::string ProfileOAuth2TokenServiceIOS::AccountInfo::GetUsername() const {
+  // TODO(rogerta): when |account_id| becomes the obfuscated gaia id, this
+  // will need to be changed.
+  return account_id_;
+}
+
 GoogleServiceAuthError
 ProfileOAuth2TokenServiceIOS::AccountInfo::GetAuthStatus() const {
   return last_auth_error_;