Fix IWYU in base/files/file.h

net/disk_cache/simple/simple_test_util.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.
 
 #include "net/disk_cache/simple/simple_test_util.h"
 
 #include "base/files/file.h"
+#include "base/files/file_path.h"
 #include "net/disk_cache/simple/simple_util.h"
 
 namespace disk_cache {
 namespace simple_util {
 
 bool CreateCorruptFileForTests(const std::string& key,
                                const base::FilePath& cache_path) {
   base::FilePath entry_file_path = cache_path.AppendASCII(
       disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
   int flags = base::File::FLAG_CREATE_ALWAYS | base::File::FLAG_WRITE;
   base::File entry_file(entry_file_path, flags);
 
   if (!entry_file.IsValid())
     return false;
 
   return entry_file.Write(0, "dummy", 1) == 1;
 }
 
 }  // namespace simple_util
 }  // namespace disk_cache