Clean up a few unused globals.

base/file_util.cc

Index: base/file_util.cc
diff --git a/base/file_util.cc b/base/file_util.cc
index e9806763855f8b3cc90eb13176ca2a4d330dce11..308b150a1d6d8d2aeba7f08caa76abfba49af6e3 100644
--- a/base/file_util.cc
+++ b/base/file_util.cc
@@ -23,8 +23,6 @@ namespace base {
 
 namespace {
 
-const FilePath::CharType kExtensionSeparator = FILE_PATH_LITERAL('.');
-
 // The maximum number of 'uniquified' files we will try to create.
 // This is used when the filename we're trying to download is already in use,
 // so we create a new unique filename by appending " (nnn)" before the
@@ -157,7 +155,6 @@ namespace file_util {
 
 using base::FileEnumerator;
 using base::FilePath;
-using base::kExtensionSeparator;
 using base::kMaxUniqueFiles;
 
 bool IsDirectoryEmpty(const FilePath& dir_path) {