Revert of Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

ash/mus/sysui_application.h

 // Copyright 2016 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_MUS_SYSUI_APPLICATION_H_
 #define ASH_MUS_SYSUI_APPLICATION_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "mojo/services/tracing/public/cpp/tracing_impl.h"
 #include "mojo/shell/public/cpp/shell_client.h"
 
 namespace ash {
 namespace sysui {
 
 class AshInit;
 
 class SysUIApplication : public mojo::ShellClient {
  public:
   SysUIApplication();
   ~SysUIApplication() override;
 
  private:
   // mojo::ShellClient:
   void Initialize(mojo::Connector* connector,
                   const mojo::Identity& identity,
                   uint32_t id) override;
   bool AcceptConnection(mojo::Connection* connection) override;
+  void ShellConnectionLost() override;
 
   mojo::TracingImpl tracing_;
   scoped_ptr<AshInit> ash_init_;
 
   DISALLOW_COPY_AND_ASSIGN(SysUIApplication);
 };
 
 }  // namespace sysui
 }  // namespace ash
 
 #endif  // ASH_MUS_SYSUI_APPLICATION_H_