diff -r 000000000000 -r 6474c204b198 mobile/android/base/gfx/VirtualLayer.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/gfx/VirtualLayer.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+/* -*- 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;
+
+public class VirtualLayer extends Layer {
+    public VirtualLayer(IntSize size) {
+        super(size);
+    }
+
+    @Override
+    public void draw(RenderContext context) {
+        // No-op.
+    }
+
+    void setPositionAndResolution(int left, int top, int right, int bottom, float newResolution) {
+        // This is an optimized version of the following code:
+        // beginTransaction();
+        // try {
+        //     setPosition(new Rect(left, top, right, bottom));
+        //     setResolution(newResolution);
+        //     performUpdates(null);
+        // } finally {
+        //     endTransaction();
+        // }
+
+        // it is safe to drop the transaction lock in this instance (i.e. for the
+        // VirtualLayer that is just a shadow of what gecko is painting) because
+        // the position and resolution of this layer are always touched on the compositor
+        // thread, and therefore do not require synchronization.
+        mPosition.set(left, top, right, bottom);
+        mResolution = newResolution;
+    }
+}