[presubmit] Enable readability/namespace linter checking.

src/base/platform/condition-variable.h

 // Copyright 2013 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.
 
 #ifndef V8_BASE_PLATFORM_CONDITION_VARIABLE_H_
 #define V8_BASE_PLATFORM_CONDITION_VARIABLE_H_
 
 #include "src/base/lazy-instance.h"
 #include "src/base/platform/mutex.h"
 
@@ skipping 95 matching lines @@
 //   void my_function() {
 //     LockGuard<Mutex> lock_guard(&my_mutex);
 //     my_condvar.Pointer()->Wait(&my_mutex);
 //   }
 typedef LazyStaticInstance<
     ConditionVariable, DefaultConstructTrait<ConditionVariable>,
     ThreadSafeInitOnceTrait>::type LazyConditionVariable;
 
 #define LAZY_CONDITION_VARIABLE_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
 
-} }  // namespace v8::base
+}  // namespace base
+}  // namespace v8
 
 #endif  // V8_BASE_PLATFORM_CONDITION_VARIABLE_H_