Make common utility to load views from nibs.

ui/base/cocoa/nib_loading.h

+// 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.
+
+#ifndef UI_BASE_COCOA_NIB_LOADING_H_
+#define UI_BASE_COCOA_NIB_LOADING_H_
+#pragma once
+
+#import <Cocoa/Cocoa.h>
+
+#include "ui/base/ui_export.h"
+
+namespace ui {
+
+// Given the name of a nib file, gets an unowned reference to the NSView in the
+// nib. Requires a nib with just a single root view.
+UI_EXPORT NSView* GetViewFromNib(NSString* name);
+
+}  // namespace ui
+
+#endif  // UI_BASE_COCOA_NIB_LOADING_H_