[OSX] Remove wide->NSString conversion

chrome/browser/ui/cocoa/login_prompt_cocoa.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/login_prompt_cocoa.h"
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
 #include "base/string16.h"
 #include "base/string_util.h"
@@ skipping 134 matching lines @@
 
 - (void)dealloc {
   // The buttons could be in a modal loop, so disconnect them so they cannot
   // call back to us after we're dead.
   [loginButton_ setTarget:nil];
   [cancelButton_ setTarget:nil];
   [super dealloc];
 }
 
 - (IBAction)loginPressed:(id)sender {
-  using base::SysNSStringToWide;
   [NSApp endSheet:[self window]];
   handler_->OnLoginPressed(
       base::SysNSStringToUTF16([nameField_ stringValue]),
       base::SysNSStringToUTF16([passwordField_ stringValue]));
 }
 
 - (IBAction)cancelPressed:(id)sender {
   [NSApp endSheet:[self window]];
   handler_->OnCancelPressed();
 }
@@ skipping 23 matching lines @@
        sizeToFitFixedWidthTextField:explanationField_];
 
   // Resize the window (no shifting needed due to window layout).
   NSSize windowDelta = NSMakeSize(0, explanationShift);
   [GTMUILocalizerAndLayoutTweaker
       resizeWindowWithoutAutoResizingSubViews:[self window]
                                         delta:windowDelta];
 }
 
 @end