chromeos: Remove Introspectable D-Bus client library

chromeos/dbus/fake_introspectable_client.h

-// Copyright 2013 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 CHROMEOS_DBUS_FAKE_INTROSPECTABLE_CLIENT_H_
-#define CHROMEOS_DBUS_FAKE_INTROSPECTABLE_CLIENT_H_
-
-#include "base/compiler_specific.h"
-#include "chromeos/dbus/introspectable_client.h"
-
-namespace chromeos {
-
-// The IntrospectableClient implementation used on Linux desktop, which does
-// nothing.
-class FakeIntrospectableClient: public IntrospectableClient {
- public:
-  FakeIntrospectableClient();
-  ~FakeIntrospectableClient() override;
-
-  void Init(dbus::Bus* bus) override;
-  void Introspect(const std::string& service_name,
-                  const dbus::ObjectPath& object_path,
-                  const IntrospectCallback& callback) override;
-};
-
-}  // namespace chromeos
-
-#endif  // CHROMEOS_DBUS_INTROSPECTABLE_CLIENT_H_