Make callers of CommandLine use it via the base:: namespace.

tools/perf/clear_system_cache/clear_system_cache_main.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A utility to clear the operating system's cache for a file or directory.
 //
 // USAGE: clear_system_cache [--recurse] <files or directories>
 
 #include <stdio.h>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/test/test_file_util.h"
 
 void ClearCacheForFile(const base::FilePath& path) {
   VLOG(1) << "Clearing " << path.MaybeAsASCII();
   base::EvictFileFromSystemCache(path);
 }
 
 int main(int argc, const char* argv[]) {
-  CommandLine::Init(argc, argv);
-  const CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
+  base::CommandLine::Init(argc, argv);
+  const base::CommandLine& parsed_command_line =
+      *base::CommandLine::ForCurrentProcess();
   bool should_recurse = parsed_command_line.HasSwitch("recurse");
-  const CommandLine::StringVector& args = parsed_command_line.GetArgs();
+  const base::CommandLine::StringVector& args = parsed_command_line.GetArgs();
 
   if (args.size() < 1) {
     printf("USAGE: %s [--recurse] <files or directories>\n", argv[0]);
     return 1;
   }
 
   for (size_t i = 0; i < args.size(); ++i) {
     base::FilePath path(args[i]);
     if (!base::PathExists(path)) {
       LOG(ERROR) << "Couldn't find " << path.MaybeAsASCII();
       return 1;
     }
 
     if (base::DirectoryExists(path)) {
       base::FileEnumerator enumerator(path, should_recurse,
                                       base::FileEnumerator::FILES);
       for (base::FilePath next = enumerator.Next(); !next.empty();
            next = enumerator.Next()) {
         ClearCacheForFile(next);
       }
     } else {
       ClearCacheForFile(path);
     }
   }
 
   return 0;
 }