Move FileEnumerator to its own file, do some refactoring.

chrome/installer/util/installer_state.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 "chrome/installer/util/installer_state.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/file_version_info.h"
+#include "base/files/file_enumerator.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/win/registry.h"
 #include "base/win/scoped_handle.h"
 #include "chrome/installer/util/delete_tree_work_item.h"
 #include "chrome/installer/util/helper.h"
 #include "chrome/installer/util/install_util.h"
 #include "chrome/installer/util/installation_state.h"
@@ skipping 618 matching lines @@
   std::set<std::string> existing_version_strings;
   existing_version_strings.insert(new_version.GetString());
   if (existing_version)
     existing_version_strings.insert(existing_version->GetString());
 
   // Make sure not to delete any version dir that is "referenced" by an existing
   // Chrome executable.
   GetExistingExeVersions(&existing_version_strings);
 
   // Try to delete all directories that are not in the set we care to keep.
-  file_util::FileEnumerator version_enum(target_path(), false,
-      file_util::FileEnumerator::DIRECTORIES);
+  base::FileEnumerator version_enum(target_path(), false,
+                                    base::FileEnumerator::DIRECTORIES);
   for (base::FilePath next_version = version_enum.Next(); !next_version.empty();
        next_version = version_enum.Next()) {
     base::FilePath dir_name(next_version.BaseName());
     version = Version(WideToASCII(dir_name.value()));
     // Delete the version folder if it is less than the new version and not
     // equal to the old version (if we have an old version).
     if (version.IsValid() &&
         existing_version_strings.count(version.GetString()) == 0) {
       // Note: temporarily log old version deletion at ERROR level to make it
       // more likely we see this in the installer log.
@@ skipping 126 matching lines @@
   }
   if (!install_list->Do())
     LOG(ERROR) << "Failed to record installer error information in registry.";
 }
 
 bool InstallerState::RequiresActiveSetup() const {
   return system_install() && FindProduct(BrowserDistribution::CHROME_BROWSER);
 }
 
 }  // namespace installer