[DMC #23] Add CompositionMarker (subclass of DocumentMarker)

third_party/WebKit/Source/core/editing/markers/CompositionMarker.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 CompositionMarker_h
+#define CompositionMarker_h
+
+#include "core/editing/markers/DocumentMarker.h"
+
+namespace blink {
+
+// A subclass of DocumentMarker used to store information specific to
+// composition markers. We store what color to display the underline (possibly
+// transparent), whether the underline should be thick or not, and what
+// background color should be used under the marked text (also possibly
+// transparent).
+class CORE_EXPORT CompositionMarker final : public DocumentMarker {
+ public:
+  CompositionMarker(unsigned start_offset,
+                    unsigned end_offset,
+                    Color underline_color,
+                    bool thick,
+                    Color background_color);
+
+  Color UnderlineColor() const;
+  bool Thick() const;
+  Color BackgroundColor() const;
+
+ private:
+  const Color underline_color_;
+  const Color background_color_;
+  const bool thick_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompositionMarker);
+};
+
+DEFINE_TYPE_CASTS(CompositionMarker,
+                  DocumentMarker,
+                  marker,
+                  marker->GetType() == DocumentMarker::kComposition,
+                  marker.GetType() == DocumentMarker::kComposition);
+
+}  // namespace blink
+
+#endif