[DMC #4] Add SingletonMarkerListImpl

third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.h

Index: third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.h
diff --git a/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.h b/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.h
new file mode 100644
index 0000000000000000000000000000000000000000..250c26608bd63dc45228c0df579e66efaca139f1
--- /dev/null
+++ b/third_party/WebKit/Source/core/editing/markers/SingletonMarkerListImpl.h
@@ -0,0 +1,38 @@
+// 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 SingletonMarkerListImpl_h
+#define SingletonMarkerListImpl_h
+
+#include "core/editing/markers/DocumentMarkerList.h"
+
+namespace blink {
+
+class CORE_EXPORT SingletonMarkerListImpl : public DocumentMarkerList {
+ public:
+  SingletonMarkerListImpl() = default;
+
+  bool IsEmpty() const final;
+
+  void Add(DocumentMarker*) final;
+  void Clear() final;
+
+  void AppendMarkersToInputList(DocumentMarkerVector* list) const final;
+
+  bool MoveMarkers(int length, DocumentMarkerList* dst_list) final;
+  bool RemoveMarkers(unsigned start_offset, int length) final;
+  bool ShiftMarkers(unsigned offset,
+                    unsigned old_length,
+                    unsigned new_length) final;
+  DECLARE_TRACE();
+
+ private:
+  Member<DocumentMarker> marker_;
+
+  DISALLOW_COPY_AND_ASSIGN(SingletonMarkerListImpl);
+};
+
+}  // namespace blink
+
+#endif  // SingletonMarkerListImpl_h