Update copyright headers in base/

The methodology used to generate this CL is documented in
https://crbug.com/1098010#c34.

An earlier version of this CL, https://crrev.com/c/3879904,
was reverted due to an issue that was resolved with
https://crrev.com/c/3881211.

No-Try: true
Bug: 1098010
Change-Id: Ibd6ffb97e66835bc299fe7b85876c3e2927b2345
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3883841
Auto-Submit: Avi Drissman <[email protected]>
Owners-Override: Avi Drissman <[email protected]>
Reviewed-by: Mark Mentovai <[email protected]>
Commit-Queue: Mark Mentovai <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1044747}
diff --git a/base/atomic_ref_count.h b/base/atomic_ref_count.h
index 5e48c82..a10a8ce6 100644
--- a/base/atomic_ref_count.h
+++ b/base/atomic_ref_count.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright 2011 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.