Switch SupportsUserData uses to use unique_ptr.

components/offline_pages/core/downloads/download_notifying_observer.cc

Index: components/offline_pages/core/downloads/download_notifying_observer.cc
diff --git a/components/offline_pages/core/downloads/download_notifying_observer.cc b/components/offline_pages/core/downloads/download_notifying_observer.cc
index 00cc67daf40b3a73b6fbb24d2302e1754e4ec842..648f7f7f0a285b6dce5ff716693b696e1dde455e 100644
--- a/components/offline_pages/core/downloads/download_notifying_observer.cc
+++ b/components/offline_pages/core/downloads/download_notifying_observer.cc
@@ -4,6 +4,7 @@
 
 #include "components/offline_pages/core/downloads/download_notifying_observer.h"
 
+#include "base/memory/ptr_util.h"
 #include "components/offline_pages/core/background/request_coordinator.h"
 #include "components/offline_pages/core/background/save_page_request.h"
 #include "components/offline_pages/core/client_policy_controller.h"
@@ -36,11 +37,11 @@ void DownloadNotifyingObserver::CreateAndStartObserving(
     std::unique_ptr<OfflinePageDownloadNotifier> notifier) {
   DCHECK(request_coordinator);
   DCHECK(notifier.get());
-  DownloadNotifyingObserver* observer = new DownloadNotifyingObserver(
-      std::move(notifier), request_coordinator->GetPolicyController());
-  request_coordinator->AddObserver(observer);
-  // |request_coordinator| takes ownership of observer here.
-  request_coordinator->SetUserData(&kUserDataKey, observer);
+  std::unique_ptr<DownloadNotifyingObserver> observer =
+      base::WrapUnique(new DownloadNotifyingObserver(

[dewittj, 2017/04/28 19:02:19]

nit: rewrite this as:
auto observer =
base::MakeUnique<DownloadNotifyingObserver>(std::move(notifier)...)

[Avi (use Gerrit), 2017/04/28 21:12:51]

Sorry, but the constructor isn't public and therefore MakeUnique can't be used.

+          std::move(notifier), request_coordinator->GetPolicyController()));
+  request_coordinator->AddObserver(observer.get());
+  request_coordinator->SetUserData(&kUserDataKey, std::move(observer));
 }
 
 void DownloadNotifyingObserver::OnAdded(const SavePageRequest& request) {