Move ReadFileToString to the 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 acedc215b95cd78561889cfac241359d9ff30b30..104a367a43fb59799d836abe64cc93bd4c9e7d2f 100644
--- a/chrome/browser/chromeos/app_mode/kiosk_app_data.cc
+++ b/chrome/browser/chromeos/app_mode/kiosk_app_data.cc
@@ -112,7 +112,7 @@ class KioskAppData::IconLoader : public ImageDecoder::Delegate {
     DCHECK(task_runner_->RunsTasksOnCurrentThread());
 
     std::string data;
-    if (!file_util::ReadFileToString(base::FilePath(icon_path_), &data)) {
+    if (!base::ReadFileToString(base::FilePath(icon_path_), &data)) {
       ReportResultOnBlockingPool(FAILED_TO_LOAD);
       return;
     }