[presubmit] Enable readability/namespace linter checking.

src/base/platform/time.cc

 // 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.
 
 #include "src/base/platform/time.h"
 
 #if V8_OS_POSIX
 #include <fcntl.h>  // for O_RDONLY
 #include <sys/time.h>
 #include <unistd.h>
@@ skipping 626 matching lines @@
 }
 
 
 // static
 bool TimeTicks::KernelTimestampAvailable() {
   return kernel_tick_clock.Pointer()->Available();
 }
 
 #endif  // V8_OS_WIN
 
-} }  // namespace v8::base
+}  // namespace base
+}  // namespace v8