Use mojo SystemTray interfaces for both mash and classic ash

ash/shell_init_params.h

 // 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.
 
 #ifndef ASH_SHELL_INIT_PARAMS_H_
 #define ASH_SHELL_INIT_PARAMS_H_
 
 #include "ash/ash_export.h"
 
 namespace base {
 class SequencedWorkerPool;
 }
 
+namespace shell {
+class Connector;
+}
+
 namespace ui {
 class ContextFactory;
 }
 
 namespace ash {
 
 class ShellDelegate;
 
 struct ASH_EXPORT ShellInitParams {
   ShellDelegate* delegate = nullptr;
   ui::ContextFactory* context_factory = nullptr;
   base::SequencedWorkerPool* blocking_pool = nullptr;
+  ::shell::Connector* connector = nullptr;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_INIT_PARAMS_H_