Update SupportsUserData uses with unique_ptr.

ui/web_dialogs/web_dialog_ui.cc

Index: ui/web_dialogs/web_dialog_ui.cc
diff --git a/ui/web_dialogs/web_dialog_ui.cc b/ui/web_dialogs/web_dialog_ui.cc
index c4767024920ae221c70993243da3f4735ed395dd..484d2803ff8202f9c304e9385237089f7f10b43b 100644
--- a/ui/web_dialogs/web_dialog_ui.cc
+++ b/ui/web_dialogs/web_dialog_ui.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/lazy_instance.h"
+#include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_view_host.h"
@@ -60,8 +61,9 @@ void WebDialogUI::CloseDialog(const base::ListValue* args) {
 // static
 void WebDialogUI::SetDelegate(content::WebContents* web_contents,
                               WebDialogDelegate* delegate) {
-  web_contents->SetUserData(&kWebDialogDelegateUserDataKey,
-                            new WebDialogDelegateUserData(delegate));
+  web_contents->SetUserData(
+      &kWebDialogDelegateUserDataKey,
+      base::MakeUnique<WebDialogDelegateUserData>(delegate));
 }
 
 ////////////////////////////////////////////////////////////////////////////////