Move FileEnumerator to its own file, do some refactoring.

chrome/browser/shell_integration_win.cc

Index: chrome/browser/shell_integration_win.cc
diff --git a/chrome/browser/shell_integration_win.cc b/chrome/browser/shell_integration_win.cc
index fb1bd643b7d061084fed2ec030ee51c53bc17a58..c73fc2c066a41e12132f8f9c0d0ef798a5fa5e2c 100644
--- a/chrome/browser/shell_integration_win.cc
+++ b/chrome/browser/shell_integration_win.cc
@@ -11,6 +11,7 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/string_util.h"
@@ -392,9 +393,9 @@ int ShellIntegration::MigrateShortcutsInPathInternal(
   DCHECK(base::win::GetVersion() >= base::win::VERSION_WIN7);
 
   // Enumerate all pinned shortcuts in the given path directly.
-  file_util::FileEnumerator shortcuts_enum(
+  base::FileEnumerator shortcuts_enum(
       path, false,  // not recursive
-      file_util::FileEnumerator::FILES, FILE_PATH_LITERAL("*.lnk"));
+      base::FileEnumerator::FILES, FILE_PATH_LITERAL("*.lnk"));
 
   bool is_per_user_install =
       InstallUtil::IsPerUserInstall(chrome_exe.value().c_str());