Make the fuchsia mojo/public repo the source of truth.

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Union.java

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.mojo.bindings;
-
-import org.chromium.mojo.system.Core;
-
-/**
- * Base class for all mojo unions.
- */
-public abstract class Union {
-    /**
-     * Returns the serialization of the union. This method can close Handles.
-     *
-     * @param core the |Core| implementation used to generate handles. Only used if the data
-     *            structure being encoded contains interfaces, can be |null| otherwise.
-     */
-    public Message serialize(Core core) {
-        Encoder encoder = new Encoder(core, BindingsHelper.UNION_SIZE);
-        encoder.claimMemory(16);
-        encode(encoder, 0);
-        return encoder.getMessage();
-    }
-
-    /**
-     * Serializes this data structure using the given encoder.
-     */
-    protected abstract void encode(Encoder encoder, int offset);
-}