Move FileEnumerator to its own file, do some refactoring.

chrome/browser/chromeos/drive/file_cache.cc

Index: chrome/browser/chromeos/drive/file_cache.cc
diff --git a/chrome/browser/chromeos/drive/file_cache.cc b/chrome/browser/chromeos/drive/file_cache.cc
index 8c43f71420061c2ff66dfeacf47d78830fa4fc65..d93e0dfe87b0e3418bf9dee3950f813f1368e1de 100644
--- a/chrome/browser/chromeos/drive/file_cache.cc
+++ b/chrome/browser/chromeos/drive/file_cache.cc
@@ -7,6 +7,7 @@
 #include <vector>
 
 #include "base/file_util.h"
+#include "base/files/file_enumerator.h"
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
@@ -61,10 +62,8 @@ bool InitCachePaths(const std::vector<base::FilePath>& cache_paths) {
 // Do not remove recursively as we don't want to touch <gcache>/tmp/downloads,
 // which is used for user initiated downloads like "Save As"
 void RemoveAllFiles(const base::FilePath& directory) {
-  using file_util::FileEnumerator;
-
-  FileEnumerator enumerator(directory, false /* recursive */,
-                            FileEnumerator::FILES);
+  base::FileEnumerator enumerator(directory, false /* recursive */,
+                                  base::FileEnumerator::FILES);
   for (base::FilePath file_path = enumerator.Next(); !file_path.empty();
        file_path = enumerator.Next()) {
     DVLOG(1) << "Removing " << file_path.value();
@@ -107,10 +106,10 @@ void DeleteFilesSelectively(const base::FilePath& path_to_delete_pattern,
   // base name of |path_to_delete_pattern|.
   // If a file is not |path_to_keep|, delete it.
   bool success = true;
-  file_util::FileEnumerator enumerator(
+  base::FileEnumerator enumerator(
       path_to_delete_pattern.DirName(),
       false,  // not recursive
-      file_util::FileEnumerator::FILES,
+      base::FileEnumerator::FILES,
       path_to_delete_pattern.BaseName().value());
   for (base::FilePath current = enumerator.Next(); !current.empty();
        current = enumerator.Next()) {