Switch SupportsUserData uses to use unique_ptr.

chrome/browser/android/download/chrome_download_delegate.h

 // Copyright 2015 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_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_
 #define CHROME_BROWSER_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_
 
 #include "base/android/jni_android.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 class ChromeDownloadDelegate
     : public content::WebContentsUserData<ChromeDownloadDelegate> {
  public:
+  ~ChromeDownloadDelegate() override;
+
   // Returns true iff this request resulted in the tab creating the download
   // to close.
   static bool EnqueueDownloadManagerRequest(jobject chrome_download_delegate,
                                             bool overwrite,
                                             jobject download_info);
 
   void SetJavaRef(JNIEnv*, jobject obj);
 
   void OnDownloadStarted(const std::string& filename);
   void RequestFileAccess(intptr_t callback_id);
 
   // TODO(qinmin): consolidate this with the static function above.
   void EnqueueDownloadManagerRequest(const std::string& url,
                                      const std::string& user_agent,
                                      const base::string16& file_name,
                                      const std::string& mime_type,
                                      const std::string& cookie,
                                      const std::string& referer);
 
  private:
   explicit ChromeDownloadDelegate(content::WebContents* contents);
   friend class content::WebContentsUserData<ChromeDownloadDelegate>;
-  ~ChromeDownloadDelegate() override;
 
   // A reference to the Java ChromeDownloadDelegate object.
   jobject java_ref_;
 };
 
 bool RegisterChromeDownloadDelegate(JNIEnv* env);
 
 #endif  // CHROME_BROWSER_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_