Switch SupportsUserData uses to use unique_ptr.

ios/chrome/browser/find_in_page/find_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_FIND_IN_PAGE_FIND_TAB_HELPER_H_
 #define IOS_CHROME_BROWSER_FIND_IN_PAGE_FIND_TAB_HELPER_H_
 
 #include <Foundation/Foundation.h>
 
 #include "base/ios/block_types.h"
 #import "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
 #include "ios/web/public/web_state/web_state_observer.h"
 #import "ios/web/public/web_state/web_state_user_data.h"
 
 @class FindInPageController;
 @protocol FindInPageControllerDelegate;
 @class FindInPageModel;
 
 typedef void (^FindInPageCompletionBlock)(FindInPageModel*);
 
 // Adds support for the "Find in page" feature.
 class FindTabHelper : public web::WebStateObserver,
                       public web::WebStateUserData<FindTabHelper> {
  public:
+  ~FindTabHelper() override;
+
   enum FindDirection {
     FORWARD,
     REVERSE,
   };
 
   // Creates a FindTabHelper and attaches it to the given |web_state|.
   // |controller_delegate| can be nil.
   static void CreateForWebState(
       web::WebState* web_state,
       id<FindInPageControllerDelegate> controller_delegate);
@@ skipping 32 matching lines @@
   void PersistSearchTerm();
 
   // Restores the current find text from persistent storage.
   void RestoreSearchTerm();
 
  private:
   friend class FindTabHelperTest;
 
   FindTabHelper(web::WebState* web_state,
                 id<FindInPageControllerDelegate> controller_delegate);
-  ~FindTabHelper() override;
 
   // web::WebStateObserver.
   void NavigationItemCommitted(
       const web::LoadCommittedDetails& load_details) override;
   void WebStateDestroyed() override;
 
   // The ObjC find in page controller.
   base::scoped_nsobject<FindInPageController> controller_;
 
   DISALLOW_COPY_AND_ASSIGN(FindTabHelper);
 };
 
 #endif  // IOS_CHROME_BROWSER_FIND_IN_PAGE_FIND_TAB_HELPER_H_