Move PathExists to base namespace.

win8/test/metro_registration_helper.cc

Index: win8/test/metro_registration_helper.cc
diff --git a/win8/test/metro_registration_helper.cc b/win8/test/metro_registration_helper.cc
index dd07cf63f19e16c032bee97dbb85501942aa4ec9..202eb73eb5d97d5b61c8994d2f3375892c3baf79 100644
--- a/win8/test/metro_registration_helper.cc
+++ b/win8/test/metro_registration_helper.cc
@@ -43,7 +43,7 @@ bool RegisterTestDefaultBrowser() {
   base::FilePath chrome_exe(dir.Append(kChromeExe));
   base::FilePath registrar(dir.Append(kRegistrar));
 
-  if (!file_util::PathExists(chrome_exe) || !file_util::PathExists(registrar)) {
+  if (!base::PathExists(chrome_exe) || !base::PathExists(registrar)) {
     LOG(ERROR) << "Could not locate " << kChromeExe << " or " << kRegistrar;
     return false;
   }