Refactor DocumentMarkerController to use SynchronousMutationObserver

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

Index: third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
diff --git a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
index 4b40f5a94cb0ea35b79d74107899df6fb22a2488..c0bc483065b3bbf6133f2e39d4a810aa13fa171c 100644
--- a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
+++ b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
@@ -82,8 +82,10 @@ inline bool DocumentMarkerController::possiblyHasMarkers(
   return m_possiblyExistingMarkerTypes.intersects(types);
 }
 
-DocumentMarkerController::DocumentMarkerController(const Document& document)
-    : m_possiblyExistingMarkerTypes(0), m_document(&document) {}
+DocumentMarkerController::DocumentMarkerController(Document& document)
+    : m_possiblyExistingMarkerTypes(0), m_document(&document) {
+  setContext(&document);
+}
 
 void DocumentMarkerController::clear() {
   m_markers.clear();
@@ -591,6 +593,7 @@ void DocumentMarkerController::invalidateRectsForAllMarkers() {
 DEFINE_TRACE(DocumentMarkerController) {
   visitor->trace(m_markers);
   visitor->trace(m_document);
+  SynchronousMutationObserver::trace(visitor);
 }
 
 void DocumentMarkerController::removeMarkers(
@@ -868,6 +871,17 @@ void DocumentMarkerController::showMarkers() const {
 }
 #endif
 
+// SynchronousMutationObserver
+void DocumentMarkerController::didUpdateCharacterData(CharacterData* node,
+                                                      unsigned offset,
+                                                      unsigned oldLength,
+                                                      unsigned newLength) {
+  // Shift markers as if we first remove the old text, then insert the new text
+  removeMarkers(node, offset, oldLength);
+  shiftMarkers(node, offset + oldLength, 0 - oldLength);
+  shiftMarkers(node, offset, newLength);
+}
+
 }  // namespace blink
 
 #ifndef NDEBUG