Switch SupportsUserData uses to use unique_ptr.

chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.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 CHROME_BROWSER_UI_EXCLUSIVE_ACCESS_FULLSCREEN_WITHIN_TAB_HELPER_H_
 #define CHROME_BROWSER_UI_EXCLUSIVE_ACCESS_FULLSCREEN_WITHIN_TAB_HELPER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 // Helper used by FullscreenController to track the state of a WebContents that
 // is in fullscreen mode, but the browser window is not. See
 // 'FullscreenWithinTab Note' in fullscreen_controller.h.
 //
 // The purpose of this class is to associate some fullscreen state at the tab
 // level rather than at the Browser level. This allows tabs to be
 // dragged/dropped between Browsers and have their fullscreen state handed off
 // between FullscreenControllers as well.
 //
 // FullscreenWithinTabHelper is created on-demand, and its lifecycle is tied to
 // that of its associated WebContents. It is automatically destroyed.
 class FullscreenWithinTabHelper
     : public content::WebContentsUserData<FullscreenWithinTabHelper> {
  public:
+  ~FullscreenWithinTabHelper() override;
+
   bool is_fullscreen_for_captured_tab() const {
     return is_fullscreen_for_captured_tab_;
   }
 
   void SetIsFullscreenForCapturedTab(bool is_fullscreen) {
     is_fullscreen_for_captured_tab_ = is_fullscreen;
   }
 
   // Immediately remove and destroy the FullscreenWithinTabHelper instance
   // associated with |web_contents|.
   static void RemoveForWebContents(content::WebContents* web_contents);
 
  private:
   friend class content::WebContentsUserData<FullscreenWithinTabHelper>;
   explicit FullscreenWithinTabHelper(content::WebContents* ignored);
-  ~FullscreenWithinTabHelper() override;
 
   bool is_fullscreen_for_captured_tab_;
 
   DISALLOW_COPY_AND_ASSIGN(FullscreenWithinTabHelper);
 };
 
 #endif  // CHROME_BROWSER_UI_EXCLUSIVE_ACCESS_FULLSCREEN_WITHIN_TAB_HELPER_H_