Revert of Move content's shell connections to the IO thread

services/navigation/navigation.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 SERVICES_NAVIGATION_NAVIGATION_H_
 #define SERVICES_NAVIGATION_NAVIGATION_H_
 
-#include "base/memory/ref_counted.h"
-#include "base/sequenced_task_runner.h"
-#include "content/public/common/connection_filter.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "services/navigation/public/interfaces/view.mojom.h"
 #include "services/shell/public/cpp/interface_factory.h"
 #include "services/shell/public/cpp/service.h"
 #include "services/shell/public/cpp/service_context_ref.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace navigation {
 
-class Navigation : public content::ConnectionFilter,
+class Navigation : public shell::Service,
                    public shell::InterfaceFactory<mojom::ViewFactory>,
                    public mojom::ViewFactory {
  public:
   Navigation();
   ~Navigation() override;
 
  private:
-  // content::ConnectionFilter:
-  bool OnConnect(shell::Connection* connection,
-                 shell::Connector* connector) override;
+  // shell::Service:
+  void OnStart(shell::Connector* connector,
+               const shell::Identity& identity,
+               uint32_t instance_id) override;
+  bool OnConnect(shell::Connection* connection) override;
 
   // shell::InterfaceFactory<mojom::ViewFactory>:
   void Create(shell::Connection* connection,
               mojom::ViewFactoryRequest request) override;
 
   // mojom::ViewFactory:
   void CreateView(mojom::ViewClientPtr client,
                   mojom::ViewRequest request) override;
 
   void ViewFactoryLost();
 
-  scoped_refptr<base::SequencedTaskRunner> view_task_runner_;
-
   shell::Connector* connector_ = nullptr;
   std::string client_user_id_;
 
   shell::ServiceContextRefFactory ref_factory_;
   std::set<std::unique_ptr<shell::ServiceContextRef>> refs_;
 
   mojo::BindingSet<mojom::ViewFactory> bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(Navigation);
 };
 
 }  // navigation
 
 #endif  // SERVICES_NAVIGATION_NAVIGATION_H_