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

ios/web/shell/shell_main_delegate.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_MAIN_DELEGATE_H_
 #define IOS_WEB_SHELL_SHELL_MAIN_DELEGATE_H_
 
+#include <memory>
+
 #include "base/compiler_specific.h"
-#include "base/memory/scoped_ptr.h"
 #include "ios/web/public/app/web_main_delegate.h"
 
 namespace web {
 class ShellWebClient;
 
 class ShellMainDelegate : public WebMainDelegate {
  public:
   ShellMainDelegate();
   ~ShellMainDelegate() override;
 
   void BasicStartupComplete() override;
 
  private:
-  scoped_ptr<ShellWebClient> web_client_;
+  std::unique_ptr<ShellWebClient> web_client_;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_SHELL_SHELL_MAIN_DELEGATE_H_