Remove SimpleBroker and instead use the production broker implementation in tests.

mojo/edk/system/simple_broker.h

-// 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.
-
-#ifndef MOJO_EDK_SYSTEM_SIMPLE_BROKER_H_
-#define MOJO_EDK_SYSTEM_SIMPLE_BROKER_H_
-
-#include "mojo/edk/system/broker.h"
-
-namespace mojo {
-namespace edk {
-
-// A simple implementation of Broker interface. This isn't meant for production
-// use (i.e. with multi-process, sandboxes). It's provided for use by unittests.
-// Implementation note: this default implementation works across processes
-// without a sandbox.
-class MOJO_SYSTEM_IMPL_EXPORT SimpleBroker : public Broker {
- public:
-  SimpleBroker();
-  ~SimpleBroker() override;
-
-  // Broker implementation:
-#if defined(OS_WIN)
-  void CreatePlatformChannelPair(ScopedPlatformHandle* server,
-                                 ScopedPlatformHandle* client) override;
-  void HandleToToken(const PlatformHandle* platform_handles,
-                     size_t count,
-                     uint64_t* tokens) override;
-  void TokenToHandle(const uint64_t* tokens,
-                     size_t count,
-                     PlatformHandle* handles) override;
-#endif
-};
-
-}  // namespace edk
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_SIMPLE_BROKER_H_