Switch SupportsUserData uses to use unique_ptr.

chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h

Index: chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h
diff --git a/chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h b/chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h
index d051bc674fe984c358e4f64e9688f78e3a787fd9..e201bb79c723ed8eb9ed1560a955a1cd33b8626a 100644
--- a/chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h
+++ b/chrome/browser/ui/exclusive_access/fullscreen_within_tab_helper.h
@@ -22,6 +22,8 @@
 class FullscreenWithinTabHelper
     : public content::WebContentsUserData<FullscreenWithinTabHelper> {
  public:
+  ~FullscreenWithinTabHelper() override;
+
   bool is_fullscreen_for_captured_tab() const {
     return is_fullscreen_for_captured_tab_;
   }
@@ -37,7 +39,6 @@ class FullscreenWithinTabHelper
  private:
   friend class content::WebContentsUserData<FullscreenWithinTabHelper>;
   explicit FullscreenWithinTabHelper(content::WebContents* ignored);
-  ~FullscreenWithinTabHelper() override;
 
   bool is_fullscreen_for_captured_tab_;