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

chrome/browser/platform_util_linux.cc

Index: chrome/browser/platform_util_linux.cc
diff --git a/chrome/browser/platform_util_linux.cc b/chrome/browser/platform_util_linux.cc
index 9ac22d7988ea764a6229ed5a1b7c94e79897c51e..6f88b16a2a2fec0a62f264bf210876f7553d2153 100644
--- a/chrome/browser/platform_util_linux.cc
+++ b/chrome/browser/platform_util_linux.cc
@@ -56,7 +56,7 @@ void XDGEmail(const std::string& email) {
 // show the folder.
 void ShowItemInFolderOnFileThread(const base::FilePath& full_path) {
   base::FilePath dir = full_path.DirName();
-  if (!file_util::DirectoryExists(dir))
+  if (!base::DirectoryExists(dir))
     return;
 
   XDGOpen(dir.value());