Rewrite base::Bind into base::BindOnce on trivial cases in base

base/observer_list_threadsafe.h

Index: base/observer_list_threadsafe.h
diff --git a/base/observer_list_threadsafe.h b/base/observer_list_threadsafe.h
index afb1010b67c4f632c055e6afb8eef21c0addd04d..c1d543edd4586e4a60e56c1774431d35fb290e94 100644
--- a/base/observer_list_threadsafe.h
+++ b/base/observer_list_threadsafe.h
@@ -151,8 +151,8 @@ class ObserverListThreadSafe
       ObserverListContext* context = entry.second.get();
       context->task_runner->PostTask(
           from_here,
-          Bind(&ObserverListThreadSafe<ObserverType>::NotifyWrapper,
-               this, context, method));
+          BindOnce(&ObserverListThreadSafe<ObserverType>::NotifyWrapper, this,
+                   context, method));
     }
   }