Move ReadFileToString to the base namespace.

chrome/common/extensions/manifest_handlers/content_scripts_handler.cc

Index: chrome/common/extensions/manifest_handlers/content_scripts_handler.cc
diff --git a/chrome/common/extensions/manifest_handlers/content_scripts_handler.cc b/chrome/common/extensions/manifest_handlers/content_scripts_handler.cc
index 7f3377dfc46f7470e1f9b177dbc2a310d3a3ecbb..a0ce28e67d6e845f870f652558e4b74cc29c8077 100644
--- a/chrome/common/extensions/manifest_handlers/content_scripts_handler.cc
+++ b/chrome/common/extensions/manifest_handlers/content_scripts_handler.cc
@@ -297,7 +297,7 @@ static bool IsScriptValid(const base::FilePath& path,
                           std::string* error) {
   std::string content;
   if (!base::PathExists(path) ||
-      !file_util::ReadFileToString(path, &content)) {
+      !base::ReadFileToString(path, &content)) {
     *error = l10n_util::GetStringFUTF8(
         message_id,
         relative_path.LossyDisplayName());