Switch SupportsUserData uses to use unique_ptr.

chrome/browser/download/download_path_reservation_tracker.cc

Index: chrome/browser/download/download_path_reservation_tracker.cc
diff --git a/chrome/browser/download/download_path_reservation_tracker.cc b/chrome/browser/download/download_path_reservation_tracker.cc
index 2c74a39535ba2687aeee037b35069a58c882a2b5..c3373d508677accb4bd48e121d1b6bdef53e1e7a 100644
--- a/chrome/browser/download/download_path_reservation_tracker.cc
+++ b/chrome/browser/download/download_path_reservation_tracker.cc
@@ -15,6 +15,7 @@
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
@@ -62,10 +63,9 @@ class DownloadItemObserver : public DownloadItem::Observer,
                              public base::SupportsUserData::Data {
  public:
   explicit DownloadItemObserver(DownloadItem* download_item);
-
- private:
   ~DownloadItemObserver() override;
 
+ private:
   // DownloadItem::Observer
   void OnDownloadUpdated(DownloadItem* download) override;
   void OnDownloadDestroyed(DownloadItem* download) override;
@@ -338,7 +338,7 @@ DownloadItemObserver::DownloadItemObserver(DownloadItem* download_item)
       last_target_path_(download_item->GetTargetFilePath()) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   download_item_->AddObserver(this);
-  download_item_->SetUserData(&kUserDataKey, this);
+  download_item_->SetUserData(&kUserDataKey, base::WrapUnique(this));
 }
 
 DownloadItemObserver::~DownloadItemObserver() {