[presubmit] Enable readability/namespace linter checking.

src/base/lazy-instance.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.
 
 // The LazyInstance<Type, Traits> class manages a single instance of Type,
 // which will be lazily created on the first time it's accessed.  This class is
 // useful for places you would normally use a function-level static, but you
 // need to have guaranteed thread-safety.  The Type constructor will only ever
 // be called once, even if two threads are racing to create the object.  Get()
 // and Pointer() will always return the same, completely initialized instance.
@@ skipping 214 matching lines @@
 
 template <typename T,
           typename CreateTrait = DefaultCreateTrait<T>,
           typename InitOnceTrait = ThreadSafeInitOnceTrait,
           typename DestroyTrait = LeakyInstanceTrait<T> >
 struct LazyDynamicInstance {
   typedef LazyInstanceImpl<T, DynamicallyAllocatedInstanceTrait<T>,
       CreateTrait, InitOnceTrait, DestroyTrait> type;
 };
 
-} }  // namespace v8::base
+}  // namespace base
+}  // namespace v8
 
 #endif  // V8_BASE_LAZY_INSTANCE_H_