Move ReadFileToString to the base namespace.

net/tools/tld_cleanup/tld_cleanup_util.cc

Index: net/tools/tld_cleanup/tld_cleanup_util.cc
diff --git a/net/tools/tld_cleanup/tld_cleanup_util.cc b/net/tools/tld_cleanup/tld_cleanup_util.cc
index dfa26206f9891f401a3c602d4a4a9fba6e3c3f20..8e04b55bd1cfe309be51cb0c926cf1aab3998fb2 100644
--- a/net/tools/tld_cleanup/tld_cleanup_util.cc
+++ b/net/tools/tld_cleanup/tld_cleanup_util.cc
@@ -233,7 +233,7 @@ NormalizeResult NormalizeFile(const base::FilePath& in_filename,
                               const base::FilePath& out_filename) {
   RuleMap rules;
   std::string data;
-  if (!file_util::ReadFileToString(in_filename, &data)) {
+  if (!base::ReadFileToString(in_filename, &data)) {
     LOG(ERROR) << "Unable to read file";
     // We return success since we've already reported the error.
     return kSuccess;