Convert //ios from scoped_ptr to std::unique_ptr.

ios/web/shell/shell_web_client.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 IOS_WEB_SHELL_SHELL_WEB_CLIENT_H_
 #define IOS_WEB_SHELL_SHELL_WEB_CLIENT_H_
 
+#include <memory>
+
 #include "base/compiler_specific.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "ios/web/public/web_client.h"
 
 namespace web {
 class ShellBrowserState;
 class ShellWebMainParts;
 
 class ShellWebClient : public WebClient {
  public:
   ShellWebClient();
   ~ShellWebClient() override;
 
   // WebClient implementation.
   WebMainParts* CreateWebMainParts() override;
   std::string GetProduct() const override;
   std::string GetUserAgent(bool desktop_user_agent) const override;
 
   ShellBrowserState* browser_state() const;
 
  private:
-  scoped_ptr<ShellWebMainParts> web_main_parts_;
+  std::unique_ptr<ShellWebMainParts> web_main_parts_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellWebClient);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_SHELL_SHELL_WEB_CLIENT_H_