Rewrite 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..060c6b305b1149c465c58af5e5a460c015493c06 100644
--- a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
+++ b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.h
@@ -30,6 +30,7 @@
 #define DocumentMarkerController_h
 
 #include "core/CoreExport.h"
+#include "core/dom/SynchronousMutationObserver.h"
 #include "core/editing/iterators/TextIterator.h"
 #include "core/editing/markers/DocumentMarker.h"
 #include "platform/geometry/IntRect.h"
@@ -53,11 +54,13 @@ 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,
@@ -105,7 +108,6 @@ class CORE_EXPORT DocumentMarkerController final
   void removeMarkers(const MarkerRemoverPredicate& shouldRemoveMarker);
   void repaintMarkers(
       DocumentMarker::MarkerTypes = DocumentMarker::AllMarkers());
-  void shiftMarkers(Node*, unsigned startOffset, int delta);
   // Returns true if markers within a range are found.
   bool setMarkersActive(const EphemeralRange&, bool);
   // Returns true if markers within a range defined by a node, |startOffset| and
@@ -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&);