Revert of Move UndoStack from Page to Editor

third_party/WebKit/Source/core/page/Page.h

Index: third_party/WebKit/Source/core/page/Page.h
diff --git a/third_party/WebKit/Source/core/page/Page.h b/third_party/WebKit/Source/core/page/Page.h
index c22f2b0c1d501f9d371a2141cd52ad7041e6c97c..b56d35aa02a9b090247719f2c2a1777ceb2fc547 100644
--- a/third_party/WebKit/Source/core/page/Page.h
+++ b/third_party/WebKit/Source/core/page/Page.h
@@ -62,6 +62,7 @@
 class ScrollingCoordinator;
 class Settings;
 class SpellCheckerClient;
+class UndoStack;
 class ValidationMessageClient;
 class WebLayerTreeView;
 
@@ -123,6 +124,7 @@
 
     EditorClient& editorClient() const { return *m_editorClient; }
     SpellCheckerClient& spellCheckerClient() const { return *m_spellCheckerClient; }
+    UndoStack& undoStack() const { return *m_undoStack; }
 
     void setMainFrame(Frame*);
     Frame* mainFrame() const { return m_mainFrame; }
@@ -224,6 +226,7 @@
     const Member<ContextMenuController> m_contextMenuController;
     const Member<PointerLockController> m_pointerLockController;
     Member<ScrollingCoordinator> m_scrollingCoordinator;
+    const Member<UndoStack> m_undoStack;
 
     // Typically, the main frame and Page should both be owned by the embedder,
     // which must call Page::willBeDestroyed() prior to destroying Page. This