Move UndoStack from Page to Editor

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

Index: third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
diff --git a/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp b/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
index 778e50f556ffbc4e5bc36735d705130aae9856a5..7c50a2942978072a03f64afddd4fc47f45682075 100644
--- a/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
+++ b/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
@@ -63,23 +63,12 @@ void UndoStack::registerRedoStep(UndoStep* step)
     m_redoStack.append(step);
 }
 
-void UndoStack::didUnloadFrame(const LocalFrame& frame)
+void UndoStack::didUnloadFrame()
 {
+    // TODO(xiaochengh): What's the use of this scope? Can we remove it?

[yosin_UTC9, 2016/07/01 09:21:21]

This event scope to prevent JavaScript event handlers to destruct |frame|.
Since JavaScript is never executed during |m_{undo,redo}Stack.clear()|, we can
remove this |EventDispatchForbiddenScope|.

[Xiaocheng, 2016/07/04 06:29:23]

Thanks. This method is removed.

     EventDispatchForbiddenScope assertNoEventDispatch;
-    filterOutUndoSteps(m_undoStack, frame);
-    filterOutUndoSteps(m_redoStack, frame);
-}
-
-void UndoStack::filterOutUndoSteps(UndoStepStack& stack, const LocalFrame& frame)
-{
-    UndoStepStack newStack;
-    while (!stack.isEmpty()) {
-        UndoStep* step = stack.first().get();
-        if (!step->belongsTo(frame))
-            newStack.append(step);
-        stack.removeFirst();
-    }
-    stack.swap(newStack);
+    m_undoStack.clear();
+    m_redoStack.clear();
 }
 
 bool UndoStack::canUndo() const