diff -r 000000000000 -r 6474c204b198 layout/base/nsLayoutHistoryState.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsLayoutHistoryState.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,96 @@
+/* -*- 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/. */
+
+/*
+ * container for information saved in session history when the document
+ * is not
+ */
+
+#include "nsILayoutHistoryState.h"
+#include "nsWeakReference.h"
+#include "nsClassHashtable.h"
+#include "nsPresState.h"
+#include "mozilla/Attributes.h"
+
+class nsLayoutHistoryState MOZ_FINAL : public nsILayoutHistoryState,
+                                       public nsSupportsWeakReference
+{
+public:
+  nsLayoutHistoryState()
+    : mScrollPositionOnly(false)
+  {
+  }
+
+  NS_DECL_ISUPPORTS
+
+  // nsILayoutHistoryState
+  virtual void
+  AddState(const nsCString& aKey, nsPresState* aState) MOZ_OVERRIDE;
+  virtual nsPresState*
+  GetState(const nsCString& aKey) MOZ_OVERRIDE;
+  virtual void
+  RemoveState(const nsCString& aKey) MOZ_OVERRIDE;
+  virtual bool
+  HasStates() const MOZ_OVERRIDE;
+  virtual void
+  SetScrollPositionOnly(const bool aFlag) MOZ_OVERRIDE;
+
+
+private:
+  ~nsLayoutHistoryState() {}
+  bool mScrollPositionOnly;
+
+  nsClassHashtable<nsCStringHashKey,nsPresState> mStates;
+};
+
+
+already_AddRefed<nsILayoutHistoryState>
+NS_NewLayoutHistoryState()
+{
+  nsRefPtr<nsLayoutHistoryState> state = new nsLayoutHistoryState();
+  return state.forget();
+}
+
+NS_IMPL_ISUPPORTS(nsLayoutHistoryState,
+                  nsILayoutHistoryState,
+                  nsISupportsWeakReference)
+
+void
+nsLayoutHistoryState::AddState(const nsCString& aStateKey, nsPresState* aState)
+{
+  mStates.Put(aStateKey, aState);
+}
+
+nsPresState*
+nsLayoutHistoryState::GetState(const nsCString& aKey)
+{
+  nsPresState* state = nullptr;
+  bool entryExists = mStates.Get(aKey, &state);
+
+  if (entryExists && mScrollPositionOnly) {
+    // Ensure any state that shouldn't be restored is removed
+    state->ClearNonScrollState();
+  }
+
+  return state;
+}
+
+void
+nsLayoutHistoryState::RemoveState(const nsCString& aKey)
+{
+  mStates.Remove(aKey);
+}
+
+bool
+nsLayoutHistoryState::HasStates() const
+{
+  return mStates.Count() != 0;
+}
+
+void
+nsLayoutHistoryState::SetScrollPositionOnly(const bool aFlag)
+{
+  mScrollPositionOnly = aFlag;
+}