Move FileEnumerator to its own file, do some refactoring.

net/tools/quic/quic_in_memory_cache.cc

 // Copyright (c) 2012 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/tools/quic/quic_in_memory_cache.h"
 
 #include "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "base/stl_util.h"
 
 using base::FilePath;
 using base::StringPiece;
-using file_util::FileEnumerator;
 using std::string;
 
 // Specifies the directory used during QuicInMemoryCache
 // construction to seed the cache. Cache directory can be
 // generated using `wget -p --save-headers <url>
 string FLAGS_quic_in_memory_cache_dir;
 
 namespace net {
 namespace tools {
 
@@ skipping 89 matching lines @@
 QuicInMemoryCache::QuicInMemoryCache() {
   // If there's no defined cache dir, we have no initialization to do.
   if (FLAGS_quic_in_memory_cache_dir.empty()) {
     LOG(WARNING) << "No cache directory found. Skipping initialization.";
     return;
   }
   LOG(INFO) << "Attempting to initialize QuicInMemoryCache from directory: "
             << FLAGS_quic_in_memory_cache_dir;
 
   FilePath directory(FLAGS_quic_in_memory_cache_dir);
-  FileEnumerator file_list(directory,
-                           true,
-                           FileEnumerator::FILES);
+  base::FileEnumerator file_list(directory,
+                                 true,
+                                 base::FileEnumerator::FILES);
 
   FilePath file = file_list.Next();
   while (!file.empty()) {
     BalsaHeaders request_headers, response_headers;
 
     string file_contents;
     file_util::ReadFileToString(file, &file_contents);
 
     // Frame HTTP.
     CachingBalsaVisitor caching_visitor;
@@ skipping 59 matching lines @@
   STLDeleteValues(&responses_);
 }
 
 string QuicInMemoryCache::GetKey(const BalsaHeaders& request_headers) const {
   return request_headers.GetHeader("host").as_string() +
       request_headers.request_uri().as_string();
 }
 
 }  // namespace tools
 }  // namespace net