Make base compile with no "using base::FilePath".

base/file_util_linux.cc

 // Copyright (c) 2011 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.
 
 #include "base/file_util.h"
 
 #include "base/file_path.h"
 
 #include <errno.h>
 #include <sys/vfs.h>
 
 namespace file_util {
 
-bool GetFileSystemType(const FilePath& path, FileSystemType* type) {
+bool GetFileSystemType(const base::FilePath& path, FileSystemType* type) {
   struct statfs statfs_buf;
   if (statfs(path.value().c_str(), &statfs_buf) < 0) {
     if (errno == ENOENT)
       return false;
     *type = FILE_SYSTEM_UNKNOWN;
     return true;
   }
 
   // While you would think the possible values of f_type would be available
   // in a header somewhere, it appears that is not the case.  These values
@@ skipping 28 matching lines @@
     case 0x27e0eb: // CGROUP
       *type = FILE_SYSTEM_CGROUP;
       break;
     default:
       *type = FILE_SYSTEM_OTHER;
   }
   return true;
 }
 
 }  // namespace