Add CompositionMarkerList in preparation for DocumentMarkerController refactor

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

Index: third_party/WebKit/Source/core/editing/markers/CompositionMarkerList.h
diff --git a/third_party/WebKit/Source/core/editing/markers/CompositionMarkerList.h b/third_party/WebKit/Source/core/editing/markers/CompositionMarkerList.h
new file mode 100644
index 0000000000000000000000000000000000000000..aa9804aff4b94c0cf7ecdce22545897073cde51d
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+++ b/third_party/WebKit/Source/core/editing/markers/CompositionMarkerList.h
@@ -0,0 +1,23 @@
+// 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 CompositionMarkerList_h
+#define CompositionMarkerList_h
+
+#include "core/editing/markers/EditingMarkerList.h"
+
+namespace blink {
+
+class CORE_EXPORT CompositionMarkerList final : public EditingMarkerList {
+ public:
+  explicit CompositionMarkerList(DocumentMarkerController*);
+
+  DocumentMarker::MarkerType allowedMarkerType() const final;
+
+  DISALLOW_COPY_AND_ASSIGN(CompositionMarkerList);
+};
+
+}  // namespace blink
+
+#endif  // CompositionMarkerList_h