Switch SupportsUserData uses to use unique_ptr.

ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h

Index: ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h
diff --git a/ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h b/ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h
index c7d9335d721d1446424b1cb4828dc9b5d7b2b52b..0df3b3a5c6d3a3b18d90d0faacbff03b40258844 100644
--- a/ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h
+++ b/ios/chrome/browser/ssl/captive_portal_detector_tab_helper.h
@@ -19,13 +19,13 @@ class WebState;
 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_;