[presubmit] Enable readability/namespace linter checking.

src/base/atomicops_internals_portable.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file is an internal atomic implementation, use atomicops.h instead.
 
 #ifndef V8_BASE_ATOMICOPS_INTERNALS_PORTABLE_H_
 #define V8_BASE_ATOMICOPS_INTERNALS_PORTABLE_H_
 
 namespace v8 {
@@ skipping 114 matching lines @@
   return __sync_add_and_fetch(ptr, 0);
 }
 
 inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
   return __sync_add_and_fetch(ptr, 0);
 }
 
 inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
   return __sync_add_and_fetch(ptr, 0);
 }
-}
-}  // namespace v8::base
+}  // namespace base
+}  // namespace v8
 
 #endif  // V8_BASE_ATOMICOPS_INTERNALS_PORTABLE_H_