Child coordinators notify their parent upon -start and -stop.

ios/clean/chrome/browser/ui/tools/tools_coordinator.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // ======                        New Architecture                         =====
 // =         This code is only used in the new iOS Chrome architecture.       =
 // ============================================================================
 
 #import "ios/clean/chrome/browser/ui/tools/tools_coordinator.h"
 
@@ skipping 17 matching lines @@
 #pragma mark - BrowserCoordinator
 
 - (void)start {
   self.menuViewController = [[MenuViewController alloc] init];
   self.menuViewController.modalPresentationStyle = UIModalPresentationCustom;
   self.menuViewController.transitioningDelegate = self;
 
   [self.context.baseViewController presentViewController:self.menuViewController
                                                 animated:self.context.animated
                                               completion:nil];
+  [super start];
 }
 
 - (void)stop {
+  [super stop];
   [self.menuViewController.presentingViewController
       dismissViewControllerAnimated:self.context.animated
                          completion:nil];
 }
 
 #pragma mark - UIViewControllerTransitioningDelegate
 
 - (id<UIViewControllerAnimatedTransitioning>)
 animationControllerForPresentedController:(UIViewController*)presented
                      presentingController:(UIViewController*)presenting
@@ skipping 18 matching lines @@
                             sourceViewController:(UIViewController*)source {
   MenuPresentationController* menuPresentation =
       [[MenuPresentationController alloc]
           initWithPresentedViewController:presented
                  presentingViewController:presenting];
   menuPresentation.toolbarCommandHandler = self.toolbarCommandHandler;
   return menuPresentation;
 }
 
 @end