[DMC #24] Add SpellingMarker and GrammarMarker (subclasses of DocumentMarker)

third_party/WebKit/Source/core/editing/markers/GrammarMarker.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 GrammarMarker_h
+#define GrammarMarker_h
+
+#include "core/editing/markers/SpellCheckMarker.h"
+
+namespace blink {
+
+class CORE_EXPORT GrammarMarker final : public SpellCheckMarker {

[yosin_UTC9, 2017/06/01 03:29:12]

Please add a class comment.

+ public:
+  GrammarMarker(unsigned start_offset,
+                unsigned end_offset,
+                const String& description);
+};

[yosin_UTC9, 2017/06/01 03:29:12]

nit: Could you add DISALLOW_COPY_AND_ASSING()?

+
+}  // namespace blink
+
+#endif