[Desktop] Add diagnostics about loading the refresh tokens.

chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h

Index: chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h
diff --git a/chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h b/chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h
index 119b5e76b49839354d208d424af05390b93ce8d7..2e5e5ab33bc5cb5a06fa95e93ea4435ccad00efc 100644
--- a/chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h
+++ b/chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.h
@@ -54,6 +54,7 @@ class MutableProfileOAuth2TokenServiceDelegate
 
   // Overridden from OAuth2TokenServiceDelegate.
   void Shutdown() override;
+  LoadCredentialsState GetLoadCredentialsState() const override;
 
   // Overridden from NetworkChangeObserver.
   void OnNetworkChanged(net::NetworkChangeNotifier::ConnectionType type)
@@ -151,6 +152,9 @@ class MutableProfileOAuth2TokenServiceDelegate
   // credentials.  This member is empty otherwise.
   std::string loading_primary_account_id_;
 
+  // The state of the load credentials operation.
+  LoadCredentialsState load_credentials_state_;
+
   ScopedVector<RevokeServerRefreshToken> server_revokes_;
 
   // Used to verify that certain methods are called only on the thread on which