diff -r 000000000000 -r 6474c204b198 layout/generic/nsIScrollbarOwner.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/generic/nsIScrollbarOwner.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+/* -*- 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/. */
+
+#ifndef nsIScrollbarOwner_h___
+#define nsIScrollbarOwner_h___
+
+#include "nsQueryFrame.h"
+
+class nsIDOMEventTarget;
+class nsIFrame;
+
+/**
+ * An interface that represents a frame which manages scrollbars.
+ */
+class nsIScrollbarOwner : public nsQueryFrame {
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsIScrollbarOwner)
+
+  /**
+   * Obtain the frame for the horizontal or vertical scrollbar, or null
+   * if there is no such box.
+   */
+  virtual nsIFrame* GetScrollbarBox(bool aVertical) = 0;
+
+  /**
+   * Show or hide scrollbars on 2 fingers touch.
+   * Subclasses should call their ScrollbarActivity's corresponding methods.
+   */
+  virtual void ScrollbarActivityStarted() const = 0;
+  virtual void ScrollbarActivityStopped() const = 0;
+};
+
+#endif