Correct iOS build for latest Xcode beta.

ios/chrome/browser/translate/before_translate_infobar_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.
 
 #include "ios/chrome/browser/translate/before_translate_infobar_controller.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 283 matching lines @@
   [_navigationBar setAutoresizingMask:resizingMask];
   base::scoped_nsobject<UIBarButtonItem> doneButton([[UIBarButtonItem alloc]
       initWithBarButtonSystemItem:UIBarButtonSystemItemDone
                            target:self
                            action:@selector(languageSelectionDone)]);
   base::scoped_nsobject<UIBarButtonItem> cancelButton([[UIBarButtonItem alloc]
       initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
                            target:self
                            action:@selector(dismissLanguageSelectionView)]);
   base::scoped_nsobject<UINavigationItem> item(
-      [[UINavigationItem alloc] initWithTitle:nil]);
+      [[UINavigationItem alloc] initWithTitle:@""]);
   [item setRightBarButtonItem:doneButton];
   [item setLeftBarButtonItem:cancelButton];
   [item setHidesBackButton:YES];
   [_navigationBar pushNavigationItem:item animated:NO];
 
   // Creates the PickerView and its controller.
   NSInteger selectedRow;
   NSInteger disabledRow;
   if (_languageSelectionType ==
       TranslateInfoBarIOSTag::BEFORE_SOURCE_LANGUAGE) {
@@ skipping 34 matching lines @@
   [super removeView];
   [self dismissLanguageSelectionView];
 }
 
 - (void)detachView {
   [super detachView];
   [self dismissLanguageSelectionView];
 }
 
 @end