code: function runBlockTransitions($log, MetaTags, $window, $transitions) {
          $transitions.onStart({}, onStart);
          $transitions.onSuccess({}, onSuccess);
          $transitions.onError({}, onError);
          function onStart(transition) {
              $window.prerenderReady = false;
          }
          function onSuccess(transition) {
              var toState = transition.$to();
              var fromState = transition.$from();
              if (!toState.metaTags) {
                  $log.debug("MetaTags - route: \"" + toState.name + "\" does not contain any metatags");
              }
              MetaTags.update(toState.metaTags, transition);
          }
          function onError(transition) {
              MetaTags.prerender.statusCode = 500;
              $window.prerenderReady = true;
          }
      }
docs: /* @ngInject