Move WriteFile and WriteFileDescriptor from file_util to base namespace.

chrome/browser/chromeos/app_mode/kiosk_app_data.cc

Index: chrome/browser/chromeos/app_mode/kiosk_app_data.cc
diff --git a/chrome/browser/chromeos/app_mode/kiosk_app_data.cc b/chrome/browser/chromeos/app_mode/kiosk_app_data.cc
index 05a0a8988a37fbb80a6f12547f7aa546c3e25858..d97c75da641706faed2def3567e23890dddd0c42 100644
--- a/chrome/browser/chromeos/app_mode/kiosk_app_data.cc
+++ b/chrome/browser/chromeos/app_mode/kiosk_app_data.cc
@@ -58,8 +58,8 @@ void SaveIconToLocalOnBlockingPool(
     CHECK(base::CreateDirectory(dir));
 
   CHECK_EQ(static_cast<int>(raw_icon->size()),
-           file_util::WriteFile(icon_path,
-                                raw_icon->data().c_str(), raw_icon->size()));
+           base::WriteFile(icon_path,
+                           raw_icon->data().c_str(), raw_icon->size()));
 }
 
 // Returns true for valid kiosk app manifest.