Let modal view controllers become first responder when presented.

ios/chrome/browser/ui/settings/settings_navigation_controller.mm

 // Copyright 2013 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/settings/settings_navigation_controller.h"
 
 #include "base/ios/ios_util.h"
 #import "base/ios/weak_nsobject.h"
 #include "base/mac/foundation_util.h"
 #import "base/mac/scoped_nsobject.h"
@@ skipping 638 matching lines @@
     (UIViewController*)controller {
   NSValue* key = [self keyForController:controller];
   return [appBarContainedViewControllers_ objectForKey:key];
 }
 
 // Returns the dictionary key to use when dealing with |controller|.
 - (NSValue*)keyForController:(UIViewController*)controller {
   return [NSValue valueWithPointer:controller];
 }
 
+#pragma mark - UIResponder
+
+- (BOOL)canBecomeFirstResponder {
+  return YES;
+}
+
 @end