Refactor DocumentMarkerController to use SynchronousMutationObserver

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

Index: third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
diff --git a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
index 08b2e64320847b16760d3d3654e6b97e170044b2..d759b830964c19c5772b67eb272b1d8a3637541b 100644
--- a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
+++ b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
@@ -53,11 +53,13 @@ class MarkerRemoverPredicate final {
 };
 
 class CORE_EXPORT DocumentMarkerController final
-    : public GarbageCollected<DocumentMarkerController> {
+    : public GarbageCollected<DocumentMarkerController>,
+      public SynchronousMutationObserver {
   WTF_MAKE_NONCOPYABLE(DocumentMarkerController);
+  USING_GARBAGE_COLLECTED_MIXIN(DocumentMarkerController);
 
  public:
-  explicit DocumentMarkerController(const Document&);
+  explicit DocumentMarkerController(Document&);
 
   void clear();
   void addMarker(const Position& start,
@@ -130,6 +132,12 @@ class CORE_EXPORT DocumentMarkerController final
   void showMarkers() const;
 #endif
 
+  // SynchronousMutationObserver
+  void didUpdateCharacterData(CharacterData*,
+                              unsigned offset,
+                              unsigned oldLength,
+                              unsigned newLength) final;
+
  private:
   void addMarker(Node*, const DocumentMarker&);