diff -r 000000000000 -r 6474c204b198 layout/base/nsILayoutHistoryState.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsILayoutHistoryState.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * interface for container for information saved in session history when
+ * the document is not
+ */
+
+#ifndef _nsILayoutHistoryState_h
+#define _nsILayoutHistoryState_h
+
+#include "nsISupports.h"
+#include "nsStringFwd.h"
+
+class nsPresState;
+template<typename> class already_AddRefed;
+
+#define NS_ILAYOUTHISTORYSTATE_IID \
+{ 0x5208993e, 0xd812, 0x431e, \
+  { 0x95, 0x9c, 0xc3, 0x84, 0x5b, 0x6e, 0x5a, 0xce } }
+
+class nsILayoutHistoryState : public nsISupports {
+ public: 
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ILAYOUTHISTORYSTATE_IID)
+
+  /**
+   * Set |aState| as the state object for |aKey|.
+   * This _transfers_ownership_ of |aState| to the LayoutHistoryState.
+   * It will be freed when RemoveState() is called or when the
+   * LayoutHistoryState is destroyed.
+   */
+  virtual void AddState(const nsCString& aKey, nsPresState* aState) = 0;
+
+  /**
+   * Look up the state object for |aKey|.
+   */
+  virtual nsPresState* GetState(const nsCString& aKey) = 0;
+
+  /**
+   * Remove the state object for |aKey|.
+   */
+  virtual void RemoveState(const nsCString& aKey) = 0;
+
+  /**
+   * Check whether this history has any states in it
+   */
+  virtual bool HasStates() const = 0;
+
+  /**
+   * Sets whether this history can contain only scroll position history
+   * or all possible history
+   */
+  virtual void SetScrollPositionOnly(const bool aFlag) = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsILayoutHistoryState,
+                              NS_ILAYOUTHISTORYSTATE_IID)
+
+already_AddRefed<nsILayoutHistoryState>
+NS_NewLayoutHistoryState();
+
+#endif /* _nsILayoutHistoryState_h */
+