Create and remove |UiDevToolsServer::server_| in the same thread.

components/ui_devtools/devtools_server.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 COMPONENTS_UI_DEVTOOLS_DEVTOOLS_SERVER_H_
 #define COMPONENTS_UI_DEVTOOLS_DEVTOOLS_SERVER_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 25 matching lines @@
 
   void AttachClient(std::unique_ptr<UiDevToolsClient> client);
   void SendOverWebSocket(int connection_id, const String& message);
 
  private:
   explicit UiDevToolsServer(
       scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner);
 
   void Start(const std::string& address_string, uint16_t port);
   void StartServer(const std::string& address_string, uint16_t port);
+  void StopServer();
 
   // HttpServer::Delegate
   void OnConnect(int connection_id) override;
   void OnHttpRequest(int connection_id,
                      const net::HttpServerRequestInfo& info) override;
   void OnWebSocketRequest(int connection_id,
                           const net::HttpServerRequestInfo& info) override;
   void OnWebSocketMessage(int connection_id, const std::string& data) override;
   void OnClose(int connection_id) override;
 
   using ClientsList = std::vector<std::unique_ptr<UiDevToolsClient>>;
   using ConnectionsMap = std::map<uint32_t, UiDevToolsClient*>;
   ClientsList clients_;
   ConnectionsMap connections_;
 
   std::unique_ptr<base::Thread> thread_;
   std::unique_ptr<net::HttpServer> server_;
   scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
 
   // The server (owned by ash for now)
   static UiDevToolsServer* devtools_server_;
 
   DISALLOW_COPY_AND_ASSIGN(UiDevToolsServer);
 };
 
 }  // namespace ui_devtools
 
 #endif  // COMPONENTS_UI_DEVTOOLS_DEVTOOLS_SERVER_H_