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

third_party/WebKit/Source/core/editing/markers/CompositionMarker.cpp

+// 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.
+
+#include "core/editing/markers/CompositionMarker.h"
+
+namespace blink {
+
+CompositionMarker::CompositionMarker(unsigned start_offset,
+                                     unsigned end_offset,
+                                     Color underline_color,
+                                     bool thick,
+                                     Color background_color)
+    : DocumentMarker(DocumentMarker::kComposition, start_offset, end_offset),
+      underline_color_(underline_color),
+      background_color_(background_color),
+      thick_(thick) {}
+
+Color CompositionMarker::UnderlineColor() const {
+  return underline_color_;
+}
+
+bool CompositionMarker::Thick() const {
+  return thick_;
+}
+
+Color CompositionMarker::BackgroundColor() const {
+  return background_color_;
+}
+
+}  // namespace blink