Move FileEnumerator to its own file, do some refactoring.

net/disk_cache/block_files_unittest.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 "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "net/disk_cache/block_files.h"
 #include "net/disk_cache/disk_cache.h"
 #include "net/disk_cache/disk_cache_test_base.h"
 #include "net/disk_cache/disk_cache_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using base::Time;
 
 namespace {
 
 // Returns the number of files in this folder.
 int NumberOfFiles(const base::FilePath& path) {
-  file_util::FileEnumerator iter(path, false, file_util::FileEnumerator::FILES);
+  base::FileEnumerator iter(path, false, base::FileEnumerator::FILES);
   int count = 0;
   for (base::FilePath file = iter.Next(); !file.value().empty();
        file = iter.Next()) {
     count++;
   }
   return count;
 }
 
 }  // namespace;
 
@@ skipping 311 matching lines @@
   }
 
   // The allocation map should be empty.
   for (int i =0; i < 50; i++) {
     SCOPED_TRACE(i);
     EXPECT_EQ(0, buffer[i]);
   }
 }
 
 }  // namespace disk_cache