Move WriteFile and WriteFileDescriptor from file_util to base namespace.

chrome/test/perf/startup_test.cc

Index: chrome/test/perf/startup_test.cc
diff --git a/chrome/test/perf/startup_test.cc b/chrome/test/perf/startup_test.cc
index 34a83dd1c20ea4156c5c19298d891d95c363ab35..2f93bb0e6b6d3a66fbd5585fc0bbda46b3fa2570 100644
--- a/chrome/test/perf/startup_test.cc
+++ b/chrome/test/perf/startup_test.cc
@@ -137,7 +137,7 @@ class StartupTest : public UIPerfTest {
     subst.push_back(base::WideToUTF16(user_data_dir_w));
     const std::string prefs_string =
         UTF16ToASCII(ReplaceStringPlaceholders(format_string, subst, NULL));
-    EXPECT_TRUE(file_util::WriteFile(pref_path, prefs_string.c_str(),
+    EXPECT_TRUE(base::WriteFile(pref_path, prefs_string.c_str(),
                                      prefs_string.size()));
     file_util::EvictFileFromSystemCache(pref_path);
   }