Switch SupportsUserData uses to use unique_ptr.

ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h

 // Copyright 2017 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_CHROME_BROWSER_SSL_CAPTIVE_PORTAL_DETECTOR_TAB_HELPER_H_
 #define IOS_CHROME_BROWSER_SSL_CAPTIVE_PORTAL_DETECTOR_TAB_HELPER_H_
 
 #import "ios/web/public/web_state/web_state_user_data.h"
 
 namespace captive_portal {
 class CaptivePortalDetector;
 }
 
 namespace web {
 class WebState;
 }
 
 // Associates a Tab to a CaptivePortalDetector and manages its lifetime.
 class CaptivePortalDetectorTabHelper
     : public web::WebStateUserData<CaptivePortalDetectorTabHelper> {
  public:
+  ~CaptivePortalDetectorTabHelper() override;
+
   explicit CaptivePortalDetectorTabHelper(web::WebState* web_state);
 
   captive_portal::CaptivePortalDetector* detector();
 
  private:
-  ~CaptivePortalDetectorTabHelper() override;
-
   // The underlying CaptivePortalDetector.
   std::unique_ptr<captive_portal::CaptivePortalDetector> detector_;
 
   DISALLOW_COPY_AND_ASSIGN(CaptivePortalDetectorTabHelper);
 };
 
 #endif  // IOS_CHROME_BROWSER_SSL_CAPTIVE_PORTAL_DETECTOR_TAB_HELPER_H_