Use mojo SystemTray interfaces for both mash and classic ash

ash/shell.cc

 // Copyright (c) 2012 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 "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 589 matching lines @@
 #endif
 
   // Needs to happen right before |instance_| is reset.
   wm_shell_.reset();
 
   DCHECK(instance_ == this);
   instance_ = nullptr;
 }
 
 void Shell::Init(const ShellInitParams& init_params) {
-  wm_shell_->Initialize(init_params.blocking_pool);
+  // HACK: In real life, this would have a shell::Connector as well.
+  wm_shell_->Initialize(init_params.blocking_pool, nullptr);
 
   immersive_handler_factory_ = base::MakeUnique<ImmersiveHandlerFactoryAsh>();
 
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   NOTREACHED() << "linux desktop does not support ash.";
 #endif
 
   scoped_overview_animation_settings_factory_.reset(
       new ScopedOverviewAnimationSettingsFactoryAura);
   window_positioner_.reset(new WindowPositioner(wm_shell_.get()));
@@ skipping 315 matching lines @@
 std::unique_ptr<ui::EventTargetIterator> Shell::GetChildIterator() const {
   return std::unique_ptr<ui::EventTargetIterator>();
 }
 
 ui::EventTargeter* Shell::GetEventTargeter() {
   NOTREACHED();
   return nullptr;
 }
 
 }  // namespace ash