[MacViews] Implemented text context menu

ui/gfx/decorated_text_mac.h

+// Copyright 2017 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_GFX_DECORATED_TEXT_MAC_H_
+#define UI_GFX_DECORATED_TEXT_MAC_H_
+
+#include "ui/gfx/gfx_export.h"
+
+@class NSAttributedString;
+
+namespace gfx {
+
+struct DecoratedText;
+
+// Returns a NSAttributedString from |decorated_text|.
+GFX_EXPORT NSAttributedString* GetAttributedStringFromDecoratedText(
+    const DecoratedText& decorated_text);
+
+}  // namespace gfx
+
+#endif  // UI_GFX_DECORATED_TEXT_MAC_H_