Coordinators: let the presenting view controller dismiss.

ios/clean/chrome/browser/ui/settings/settings_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/settings/settings_coordinator.h"
 
@@ skipping 20 matching lines @@
   self.viewController = [SettingsNavigationController
       newSettingsMainControllerWithMainBrowserState:self.browserState
                                 currentBrowserState:self.browserState
                                            delegate:self];
   [self.baseViewController presentViewController:self.viewController
                                         animated:self.context.animated
                                       completion:nil];
 }
 
 - (void)stop {
-  [self.viewController dismissViewControllerAnimated:self.context.animated
-                                          completion:nil];
+  [self.viewController.presentingViewController
+      dismissViewControllerAnimated:self.context.animated
+                         completion:nil];
 }
 
 #pragma mark - SettingsNavigationControllerDelegate
 
 - (void)closeSettingsAndOpenUrl:(OpenUrlCommand*)command {
   // Placeholder implementation to conform to the delegate protocol;
   // for now this just closes the settings without opening a URL.
   [self closeSettings];
 }
 
 - (void)closeSettingsAndOpenNewIncognitoTab {
   // Placeholder implementation to conform to the delegate protocol;
   // for now this just closes the settings without opening a new tab.
   [self closeSettings];
 }
 
 - (void)closeSettings {
   [self.settingsCommandHandler closeSettings];
 }
 
 @end