Make chrome/browser/media_galleries compile on Android

chrome/browser/media_galleries/android/mtp_device_delegate_impl_android.cc

+// Copyright 2015 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.
+
+#include "chrome/browser/media_galleries/fileapi/mtp_device_async_delegate.h"
+
+void CreateMTPDeviceAsyncDelegate(
+    const std::string& device_location,
+    const bool read_only,
+    const CreateMTPDeviceAsyncDelegateCallback& callback) {
+  // Return nullptr as there is no MTPDeviceAsyncDelegate implementation for
+  // Chrome on Android at the moment.
+  // TODO(crbug.com/560390): Add an MTPDeviceAsyncDelegate implementation on
+  // Android.
+  NOTIMPLEMENTED();
+  callback.Run(nullptr);
+}