Let the MainController dismiss presented modals.

ios/chrome/browser/ui/keyboard/UIKeyCommand+Chrome.h

 // Copyright 2015 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.
 
 #ifndef IOS_CHROME_BROWSER_UI_KEYBOARD_UIKEYCOMMAND_CHROME_H_
 #define IOS_CHROME_BROWSER_UI_KEYBOARD_UIKEYCOMMAND_CHROME_H_
 
 #import <Foundation/Foundation.h>
 #import <UIKit/UIKit.h>
 
@@ skipping 39 matching lines @@
 //                                    title:@"New Tab"
 //                                   action:^{
 //       base::scoped_nsobject<Foo> strongSelf([weakSelf retain]);
 //       if (!strongSelf)
 //         return;
 //       [strongSelf openNewTab];
 //     }],
 //   ];
 // }
 //
-// Or in a UIViewController:
+// Or in a UIViewController starting in iOS 9:
 //
 // baz_view_controller.mm:
 //
 // - (void)viewDidLoad {
 //   …
 //   [self addKeyCommand:[UIKeyCommand cr_keyCommandWithInput:input
 //                                             modifierFlags:modifierFlags
 //                                                     title:title
 //                                                    action:action]];
 //   …
@@ skipping 13 matching lines @@
 + (instancetype)cr_keyCommandWithInput:(NSString*)input
                          modifierFlags:(UIKeyModifierFlags)modifierFlags
                                  title:(nullable NSString*)discoveryTitle
                                 action:(UIKeyCommandAction)action;
 
 @end
 
 NS_ASSUME_NONNULL_END
 
 #endif  // IOS_CHROME_BROWSER_UI_KEYBOARD_UIKEYCOMMAND_CHROME_H_