Let modal view controllers become first responder when presented.

ios/chrome/browser/ui/bookmarks/bookmark_navigation_controller.mm

 // Copyright 2014 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/bookmarks/bookmark_navigation_controller.h"
 
 #include "base/mac/scoped_nsobject.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_utils_ios.h"
 
 @implementation BookmarkNavigationController
@@ skipping 10 matching lines @@
   [super viewDidLoad];
   self.view.backgroundColor = [UIColor whiteColor];
 }
 
 - (BOOL)disablesAutomaticKeyboardDismissal {
   // This allows us to hide the keyboard when controllers are being displayed in
   // a modal form sheet on the iPad.
   return NO;
 }
 
+#pragma mark - UIResponder
+
+- (BOOL)canBecomeFirstResponder {
+  return YES;
+}
+
 @end