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

chrome/browser/extensions/api/file_system/file_system_api.cc

Index: chrome/browser/extensions/api/file_system/file_system_api.cc
diff --git a/chrome/browser/extensions/api/file_system/file_system_api.cc b/chrome/browser/extensions/api/file_system/file_system_api.cc
index 0e6cd76ce6c147624beb30e6edc801fd3de8feea..c02d5e011a633df8a2da4569854f4b0246ebfbcc 100644
--- a/chrome/browser/extensions/api/file_system/file_system_api.cc
+++ b/chrome/browser/extensions/api/file_system/file_system_api.cc
@@ -658,7 +658,7 @@ void FileSystemChooseEntryFunction::SetInitialPathOnFileThread(
     const base::FilePath& suggested_name,
     const base::FilePath& previous_path) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
-  if (!previous_path.empty() && file_util::DirectoryExists(previous_path)) {
+  if (!previous_path.empty() && base::DirectoryExists(previous_path)) {
     initial_path_ = previous_path.Append(suggested_name);
   } else {
     base::FilePath documents_dir;