Move ReadFileToString to the base namespace.

BUG=

Review URL: https://codereview.chromium.org/19579005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220612 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/printing/print_dialog_cloud.cc b/chrome/browser/printing/print_dialog_cloud.cc
index 49fd150..187dac6 100644
--- a/chrome/browser/printing/print_dialog_cloud.cc
+++ b/chrome/browser/printing/print_dialog_cloud.cc
@@ -671,7 +671,7 @@
     } else {
       DLOG(WARNING) << " print data file too large to reserve space";
     }
-    if (file_util::ReadFileToString(path_to_file, &file_data)) {
+    if (base::ReadFileToString(path_to_file, &file_data)) {
       data = base::RefCountedString::TakeString(&file_data);
     }
   }