Make SynchronousMutationObserver::didMergeTextNodes() to take both merged and merging nodes

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

Index: third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.h
diff --git a/third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.h b/third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.h
index f57a4816a0596e73efcfeb0c77d409421d123c77..813f2097cbe8aba08c885c1cf40476beab0389b2 100644
--- a/third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.h
+++ b/third_party/WebKit/Source/core/dom/SynchronousMutationNotifier.h
@@ -15,6 +15,7 @@ class CharacterData;
 class ContainerNode;
 class Document;
 class Node;
+class NodeWithIndex;
 class SynchronousMutationObserver;
 class Text;
 
@@ -24,7 +25,9 @@ class CORE_EXPORT SynchronousMutationNotifier
   // TODO(yosin): We will have |notifyXXX()| functions defined in
   // |SynchronousMutationObserver|.
   void notifyChangeChildren(const ContainerNode&);
-  void notifyMergeTextNodes(Text&, unsigned);
+  void notifyMergeTextNodes(const Text& mergedNode,
+                            const NodeWithIndex& nodeToBeRemovedWithIndex,
+                            unsigned oldLength);
   void notifyMoveTreeToNewDocument(const Node&);
   void notifySplitTextNode(const Text&);
   void notifyUpdateCharacterData(CharacterData*,