EDK: Add a mojo::platform::MessageLoop abstraction.

mojo/edk/base_edk/test_message_loop.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.
+
+// This file implements the factory functions declared in
+// //mojo/edk/platform/test_message_loop.h (using |mojo::platform::MessageLoop|s
+// based on //base, i.e., using |base_edk::PlatformMessageLoopImpl|).
+
+#include "mojo/edk/platform/test_message_loop.h"
+
+#include "mojo/edk/base_edk/platform_message_loop_impl.h"
+#include "mojo/edk/util/make_unique.h"
+
+using mojo::util::MakeUnique;
+
+namespace mojo {
+namespace platform {
+namespace test {
+
+std::unique_ptr<MessageLoop> CreateTestMessageLoop() {
+  return MakeUnique<base_edk::PlatformMessageLoopImpl>();
+}
+
+}  // namespace test
+}  // namespace platform
+}  // namespace mojo