Move ReadFileToString to the base namespace.

chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc

Index: chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc
diff --git a/chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc b/chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc
index cffa7cd57c9ec7c83cf2f07d49aff58aacd1d91b..380d1d6ec07abf9b8f873371ed77aa60f8147122 100644
--- a/chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc
+++ b/chrome/browser/chromeos/login/managed/locally_managed_user_login_flow.cc
@@ -30,7 +30,7 @@ std::string LoadSyncToken() {
   std::string token;
   base::FilePath token_file =
       file_util::GetHomeDir().Append(kManagedUserTokenFilename);
-  if (!file_util::ReadFileToString(token_file, &token)) {
+  if (!base::ReadFileToString(token_file, &token)) {
     return std::string();
   }
   return token;