[presubmit] Enable readability/namespace linter checking.

src/base/platform/time.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_TIME_H_
 #define V8_BASE_PLATFORM_TIME_H_
 
 #include <ctime>
 #include <iosfwd>
 #include <limits>
@@ skipping 380 matching lines @@
   explicit TimeTicks(int64_t ticks) : ticks_(ticks) {}
 
   // Tick count in microseconds.
   int64_t ticks_;
 };
 
 inline TimeTicks operator+(const TimeDelta& delta, const TimeTicks& ticks) {
   return ticks + delta;
 }
 
-} }  // namespace v8::base
+}  // namespace base
+}  // namespace v8
 
 #endif  // V8_BASE_PLATFORM_TIME_H_