diff -r 000000000000 -r 6474c204b198 mobile/android/base/gfx/Overscroll.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/gfx/Overscroll.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,21 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
+ * 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/. */
+
+package org.mozilla.gecko.gfx;
+
+import android.graphics.Canvas;
+
+public interface Overscroll {
+    // The axis to show overscroll on.
+    public enum Axis {
+        X,
+        Y,
+    };
+
+    public void draw(final Canvas canvas, final ImmutableViewportMetrics metrics);
+    public void setSize(final int width, final int height);
+    public void setVelocity(final float velocity, final Axis axis);
+    public void setDistance(final float distance, final Axis axis);
+}