Move UndoStack from Page to Editor

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

 /*
  * Copyright (C) 2006, 2007 Apple, Inc.  All rights reserved.
  * Copyright (C) 2012 Google, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 45 matching lines @@
     if (!m_inRedo)
         m_redoStack.clear();
     m_undoStack.append(step);
 }
 
 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
 {
     return !m_undoStack.isEmpty();
 }
 
 bool UndoStack::canRedo() const
 {
     return !m_redoStack.isEmpty();
@@ skipping 24 matching lines @@
     }
 }
 
 DEFINE_TRACE(UndoStack)
 {
     visitor->trace(m_undoStack);
     visitor->trace(m_redoStack);
 }
 
 } // namespace blink