Add sequence number to undo steps

third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp

Index: third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp
diff --git a/third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp b/third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp
index 1774c343bd4b279a416abf17b1d09ecdefb22783..1ad5830bf0228f4b06d27a79c279a633de5fd3d3 100644
--- a/third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp
+++ b/third_party/WebKit/Source/core/editing/commands/CompositeEditCommand.cpp
@@ -98,7 +98,8 @@ EditCommandComposition::EditCommandComposition(
       m_endingSelection(endingSelection),
       m_startingRootEditableElement(startingSelection.rootEditableElement()),
       m_endingRootEditableElement(endingSelection.rootEditableElement()),
-      m_inputType(inputType) {}
+      m_inputType(inputType),
+      m_sequence(0) {}
 
 bool EditCommandComposition::belongsTo(const LocalFrame& frame) const {
   DCHECK(m_document);
@@ -150,6 +151,14 @@ InputEvent::InputType EditCommandComposition::inputType() const {
   return m_inputType;
 }
 
+int EditCommandComposition::sequence() const {
+  return m_sequence;
+}
+
+void EditCommandComposition::setSequence(int sequence) {
+  m_sequence = sequence;
+}
+
 void EditCommandComposition::append(SimpleEditCommand* command) {
   m_commands.push_back(command);
 }