Move PathIsWritable, DirectoryExists, ContentsEqual, and TextContentsEqual to the base namespace.

chrome/browser/user_style_sheet_watcher.cc

Index: chrome/browser/user_style_sheet_watcher.cc
diff --git a/chrome/browser/user_style_sheet_watcher.cc b/chrome/browser/user_style_sheet_watcher.cc
index ddf2ba62e8d417a987317f6ddf69d677e6fe42d5..2dd64148879b4dff9f0b17c25fda73abc657da8f 100644
--- a/chrome/browser/user_style_sheet_watcher.cc
+++ b/chrome/browser/user_style_sheet_watcher.cc
@@ -104,7 +104,7 @@ void UserStyleSheetLoader::LoadStyleSheet(
   // We keep the user style sheet in a subdir so we can watch for changes
   // to the file.
   base::FilePath style_sheet_dir = style_sheet_file.DirName();
-  if (!file_util::DirectoryExists(style_sheet_dir)) {
+  if (!base::DirectoryExists(style_sheet_dir)) {
     if (!file_util::CreateDirectory(style_sheet_dir))
       return;
   }