Remove 'using base::string16;' from base/strings/string16.h and remove temporary

ui/base/cocoa/menu_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 "ui/base/cocoa/menu_controller.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/accelerators/platform_accelerator_cocoa.h"
 #import "ui/base/cocoa/cocoa_event_utils.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/models/simple_menu_model.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/text_elider.h"
 
 @interface MenuController (Private)
 - (void)addSeparatorToMenu:(NSMenu*)menu
                    atIndex:(int)index;
 @end
 
 @implementation MenuController
 
 @synthesize model = model_;
 @synthesize useWithPopUpButtonCell = useWithPopUpButtonCell_;
 
-+ (string16)elideMenuTitle:(const base::string16&)title
-                   toWidth:(int)width {
++ (base::string16)elideMenuTitle:(const base::string16&)title
+                         toWidth:(int)width {
   NSFont* nsfont = [NSFont menuBarFontOfSize:0];  // 0 means "default"
   return gfx::ElideText(title, gfx::FontList(gfx::Font(nsfont)), width,
                         gfx::ELIDE_AT_END);
 }
 
 - (id)init {
   self = [super init];
   return self;
 }
 
@@ skipping 195 matching lines @@
 }
 
 - (void)menuDidClose:(NSMenu*)menu {
   if (isMenuOpen_) {
     model_->MenuClosed();
     isMenuOpen_ = NO;
   }
 }
 
 @end