Move ReadFileToString to the base namespace.

chrome/test/perf/rendering/throughput_tests.cc

Index: chrome/test/perf/rendering/throughput_tests.cc
diff --git a/chrome/test/perf/rendering/throughput_tests.cc b/chrome/test/perf/rendering/throughput_tests.cc
index b2fc89239ce3397ce6804d38cfe4951e2770baba..1b510e3bfbe028a0d558b0ed5716dba936e1d749 100644
--- a/chrome/test/perf/rendering/throughput_tests.cc
+++ b/chrome/test/perf/rendering/throughput_tests.cc
@@ -158,7 +158,7 @@ class ThroughputTest : public BrowserPerfTest {
           flags.substr(num_pos, flags.size() - num_pos), &index));
       base::FilePath filepath(flags.substr(0, colon_pos));
       std::string json;
-      ASSERT_TRUE(file_util::ReadFileToString(filepath, &json));
+      ASSERT_TRUE(base::ReadFileToString(filepath, &json));
       ASSERT_TRUE(ParseFlagsFromJSON(filepath.DirName(), json, index));
     } else {
       gurl_ = GURL(flags);