Move ReadFileToString to the base namespace.

chrome/browser/chromeos/swap_metrics.cc

Index: chrome/browser/chromeos/swap_metrics.cc
diff --git a/chrome/browser/chromeos/swap_metrics.cc b/chrome/browser/chromeos/swap_metrics.cc
index efebac33bc87c2c7552bfbc149e206fea1a75c83..974fcc83e5df72b0e43e5c6d02e4593120731d3d 100644
--- a/chrome/browser/chromeos/swap_metrics.cc
+++ b/chrome/browser/chromeos/swap_metrics.cc
@@ -261,7 +261,7 @@ bool SwapMetrics::Backend::GetFieldFromKernelOutput(const std::string& path,
                                                     const std::string& field,
                                                     int64* value) {
   std::string file_content;
-  if (!file_util::ReadFileToString(FilePath(path), &file_content)) {
+  if (!base::ReadFileToString(FilePath(path), &file_content)) {
     LOG(WARNING) << "Cannot read " << path;
     return false;
   }
@@ -296,7 +296,7 @@ bool SwapMetrics::Backend::TokenizeOneLineFile(const std::string& path,
                                                std::vector<std::string>*
                                                tokens) {
   std::string file_content;
-  if (!file_util::ReadFileToString(FilePath(path), &file_content)) {
+  if (!base::ReadFileToString(FilePath(path), &file_content)) {
     LOG(WARNING) << "cannot read " << path;
     return false;
   }