Coordinators: let the presenting view controller dismiss.

ios/chrome/browser/ui/elements/selector_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.
 
 #import "ios/chrome/browser/ui/elements/selector_coordinator.h"
 
 #import "ios/chrome/browser/ui/elements/selector_picker_view_controller.h"
 #import "ios/chrome/browser/ui/elements/selector_picker_presentation_controller.h"
 #import "ios/chrome/browser/ui/elements/selector_view_controller_delegate.h"
 
@@ skipping 31 matching lines @@
       UIModalPresentationCustom;
   self.selectorPickerViewController.transitioningDelegate = self;
 
   [self.baseViewController
       presentViewController:self.selectorPickerViewController
                    animated:YES
                  completion:nil];
 }
 
 - (void)stop {
-  [self.selectorPickerViewController dismissViewControllerAnimated:YES
-                                                        completion:nil];
+  [self.selectorPickerViewController.presentingViewController
+      dismissViewControllerAnimated:YES
+                         completion:nil];
 }
 
 #pragma mark SelectorViewControllerDelegate
 
 - (void)selectorViewController:(UIViewController*)viewController
                didSelectOption:(NSString*)option {
   [self.delegate selectorCoordinator:self didCompleteWithSelection:option];
   [self stop];
 }
 
 #pragma mark UIViewControllerTransitioningDelegate
 
 - (UIPresentationController*)
 presentationControllerForPresentedViewController:(UIViewController*)presented
                         presentingViewController:(UIViewController*)presenting
                             sourceViewController:(UIViewController*)source {
   return [[SelectorPickerPresentationController alloc]
       initWithPresentedViewController:self.selectorPickerViewController
              presentingViewController:self.baseViewController];
 }
 
 @end