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

base/files/file_path_watcher_unittest.cc

Index: base/files/file_path_watcher_unittest.cc
diff --git a/base/files/file_path_watcher_unittest.cc b/base/files/file_path_watcher_unittest.cc
index d2ec37bbec1ba32acfb31407a8141ea1838ae36d..dcc6d5fc0f9b24c14b91d12f6edb264e4c73fb3a 100644
--- a/base/files/file_path_watcher_unittest.cc
+++ b/base/files/file_path_watcher_unittest.cc
@@ -56,8 +56,8 @@ class NotificationCollector
   // Called from the file thread by the delegates.
   void OnChange(TestDelegate* delegate) {
     task_runner_->PostTask(
-        FROM_HERE, base::Bind(&NotificationCollector::RecordChange, this,
-                              base::Unretained(delegate)));
+        FROM_HERE, base::BindOnce(&NotificationCollector::RecordChange, this,
+                                  base::Unretained(delegate)));
   }
 
   void Register(TestDelegate* delegate) {