Rewrite DocumentMarkerController to use SynchronousMutationObserver

third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.cpp

 // Copyright 2016 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/dom/SynchronousMutationNotifier.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/SynchronousMutationObserver.h"
 
 namespace blink {
 
-SynchronousMutationNotifier::SynchronousMutationNotifier() = default;
+SynchronousMutationNotifier::ScopedNotificationSuppressor::
+    ScopedNotificationSuppressor(SynchronousMutationNotifier* notifier) {
+  m_notifier = notifier;
+  m_notifier->incrementSuppressorCount();
+}
+
+SynchronousMutationNotifier::ScopedNotificationSuppressor::
+    ~ScopedNotificationSuppressor() {
+  m_notifier->decrementSuppressorCount();
+}
+
+SynchronousMutationNotifier::SynchronousMutationNotifier()
+    : m_suppressorCount(0),
+      m_pendingCharacterData(nullptr),
+      m_pendingOffset(0),
+      m_pendingOldLength(0),
+      m_pendingNewLength(0) {}
+
+DEFINE_TRACE(SynchronousMutationNotifier) {
+  visitor->trace(m_pendingCharacterData);
+  LifecycleNotifier<Document, SynchronousMutationObserver>::trace(visitor);
+}
 
 void SynchronousMutationNotifier::notifyChangeChildren(
     const ContainerNode& container) {
   for (SynchronousMutationObserver* observer : m_observers)
     observer->didChangeChildren(container);
 }
 
 void SynchronousMutationNotifier::notifyMergeTextNodes(
     const Text& node,
     const NodeWithIndex& nodeToBeRemovedWithIndex,
@@ skipping 11 matching lines @@
 void SynchronousMutationNotifier::notifySplitTextNode(const Text& node) {
   for (SynchronousMutationObserver* observer : m_observers)
     observer->didSplitTextNode(node);
 }
 
 void SynchronousMutationNotifier::notifyUpdateCharacterData(
     CharacterData* characterData,
     unsigned offset,
     unsigned oldLength,
     unsigned newLength) {
+  if (m_suppressorCount) {
+    if (!m_pendingCharacterData) {
+      m_pendingCharacterData = characterData;
+      m_pendingOffset = offset;
+      m_pendingOldLength = oldLength;
+      m_pendingNewLength = newLength;
+      return;
+    }
+
+    if (m_pendingCharacterData == characterData && m_pendingNewLength == 0 &&
+        oldLength == 0 && m_pendingOffset == offset) {
+      // insert following a delete
+      m_pendingNewLength = newLength;
+      return;
+    }
+
+    // otherwise, flush what we're currently holding and store the new update
+    // as pending
+    flushPendingCharacterDataUpdate();
+    m_pendingCharacterData = characterData;
+    m_pendingOffset = offset;
+    m_pendingOldLength = oldLength;
+    m_pendingNewLength = newLength;
+    return;
+  }
+
   for (SynchronousMutationObserver* observer : m_observers) {
     observer->didUpdateCharacterData(characterData, offset, oldLength,
                                      newLength);
   }
 }
 
 void SynchronousMutationNotifier::notifyNodeChildrenWillBeRemoved(
     ContainerNode& container) {
   for (SynchronousMutationObserver* observer : m_observers)
     observer->nodeChildrenWillBeRemoved(container);
 }
 
 void SynchronousMutationNotifier::notifyNodeWillBeRemoved(Node& node) {
   for (SynchronousMutationObserver* observer : m_observers)
     observer->nodeWillBeRemoved(node);
 }
 
+void SynchronousMutationNotifier::incrementSuppressorCount() {
+  m_suppressorCount++;
+}
+
+void SynchronousMutationNotifier::decrementSuppressorCount() {
+  m_suppressorCount--;
+  if (m_suppressorCount == 0) {
+    flushPendingCharacterDataUpdate();
+  }
+}
+
+void SynchronousMutationNotifier::notifyUpdateCharacterDataImmediately(
+    CharacterData* characterData,
+    unsigned offset,
+    unsigned oldLength,
+    unsigned newLength) {
+  for (SynchronousMutationObserver* observer : m_observers) {
+    observer->didUpdateCharacterData(characterData, offset, oldLength,
+                                     newLength);
+  }
+}
+
+void SynchronousMutationNotifier::flushPendingCharacterDataUpdate() {
+  if (!m_pendingCharacterData)
+    return;
+  notifyUpdateCharacterDataImmediately(m_pendingCharacterData, m_pendingOffset,
+                                       m_pendingOldLength, m_pendingNewLength);
+  m_pendingCharacterData = nullptr;
+}
+
 }  // namespace blink