Change gae to apache 2 license.

symbols.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
 
 package gae
 
 type stopErr struct{}
 
 func (stopErr) Error() string { return "stop iteration" }
 
 // Stop is understood by various services to stop iterative processes. Examples
 // include datastore.Interface.Run's callback.
 var Stop error = stopErr{}