Move FileEnumerator to its own file, do some refactoring.

chrome/test/perf/generate_profile.cc

Index: chrome/test/perf/generate_profile.cc
diff --git a/chrome/test/perf/generate_profile.cc b/chrome/test/perf/generate_profile.cc
index e3dd38e6a43e45e7298374a0e66c1f246bc7aecf..680d5be2f00c479ed4122f3bcab9aac246564820 100644
--- a/chrome/test/perf/generate_profile.cc
+++ b/chrome/test/perf/generate_profile.cc
@@ -7,6 +7,7 @@
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/i18n/icu_util.h"
 #include "base/logging.h"
@@ -250,8 +251,8 @@ bool GenerateProfile(GenerateProfileTypes types,
 
   message_loop.RunUntilIdle();
 
-  file_util::FileEnumerator file_iterator(profile.GetPath(), false,
-      file_util::FileEnumerator::FILES);
+  base::FileEnumerator file_iterator(profile.GetPath(), false,
+                                     base::FileEnumerator::FILES);
   base::FilePath path = file_iterator.Next();
   while (!path.empty()) {
     base::FilePath dst_file = dst_dir.Append(path.BaseName());