Move some more file utils to the base namespace.

base/file_util.cc

Index: base/file_util.cc
diff --git a/base/file_util.cc b/base/file_util.cc
index 5e9790efe46b82437db165845fc71ebaf1deef3d..1f8ba8193d90e7759d4a093d4226475b230a1712 100644
--- a/base/file_util.cc
+++ b/base/file_util.cc
@@ -145,6 +145,14 @@ bool ReadFileToString(const FilePath& path, std::string* contents) {
   return true;
 }
 
+bool IsDirectoryEmpty(const FilePath& dir_path) {
+  FileEnumerator files(dir_path, false,
+      FileEnumerator::FILES | FileEnumerator::DIRECTORIES);
+  if (files.Next().empty())
+    return true;
+  return false;
+}
+
 }  // namespace base
 
 // -----------------------------------------------------------------------------
@@ -155,14 +163,6 @@ using base::FileEnumerator;
 using base::FilePath;
 using base::kMaxUniqueFiles;
 
-bool IsDirectoryEmpty(const FilePath& dir_path) {
-  FileEnumerator files(dir_path, false,
-      FileEnumerator::FILES | FileEnumerator::DIRECTORIES);
-  if (files.Next().empty())
-    return true;
-  return false;
-}
-
 FILE* CreateAndOpenTemporaryFile(FilePath* path) {
   FilePath directory;
   if (!GetTempDir(&directory))