Change more base::ListValue methods to use std::unique_ptr.

chrome/browser/notifications/notifier_state_tracker.cc

Index: chrome/browser/notifications/notifier_state_tracker.cc
diff --git a/chrome/browser/notifications/notifier_state_tracker.cc b/chrome/browser/notifications/notifier_state_tracker.cc
index aeab48dcd2d7fbe9d7f8005daee75849e733a6e5..79f19fb69d4f25eca54a889feaaccdce970d6809 100644
--- a/chrome/browser/notifications/notifier_state_tracker.cc
+++ b/chrome/browser/notifications/notifier_state_tracker.cc
@@ -146,9 +146,9 @@ void NotifierStateTracker::SetNotifierEnabled(
   if (add_new_item) {
     // AppendIfNotPresent will delete |adding_value| when the same value
     // already exists.
-    list->AppendIfNotPresent(id.release());
+    list->AppendIfNotPresent(std::move(id));
   } else {
-    list->Remove(*id, NULL);
+    list->Remove(*id, nullptr);
   }
 }