Update copyright headers in pdf/, ppapi/, printing/

The methodology used to generate this CL is documented in
https://crbug.com/1098010#c95.

No-Try: true
Bug: 1098010
Change-Id: I6ae92e5d7ccbf73b176588124b2f8b4067f805b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3900575
Reviewed-by: Mark Mentovai <[email protected]>
Owners-Override: Avi Drissman <[email protected]>
Commit-Queue: Avi Drissman <[email protected]>
Auto-Submit: Avi Drissman <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1047628}
diff --git a/ppapi/proxy/BUILD.gn b/ppapi/proxy/BUILD.gn
index d6e1b0c..21cacd86 100644
--- a/ppapi/proxy/BUILD.gn
+++ b/ppapi/proxy/BUILD.gn
@@ -1,4 +1,4 @@
-# Copyright 2015 The Chromium Authors. All rights reserved.
+# Copyright 2015 The Chromium Authors
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.