Update from https://crrev.com/308331

base/strings/sys_string_conversions_posix.cc

Index: base/strings/sys_string_conversions_posix.cc
diff --git a/base/strings/sys_string_conversions_posix.cc b/base/strings/sys_string_conversions_posix.cc
index 1e926bb5490764f453f807c347c412210d833795..3b1845622fd300a14c2942ddf77a2a0b998825be 100644
--- a/base/strings/sys_string_conversions_posix.cc
+++ b/base/strings/sys_string_conversions_posix.cc
@@ -24,11 +24,10 @@ std::wstring SysUTF8ToWide(const StringPiece& utf8) {
   return out;
 }
 
-#if defined(OS_CHROMEOS) || defined(OS_ANDROID)
+#if defined(SYSTEM_NATIVE_UTF8) || defined(OS_ANDROID)
 // TODO(port): Consider reverting the OS_ANDROID when we have wcrtomb()
 // support and a better understanding of what calls these routines.
 
-// ChromeOS always runs in UTF-8 locale.
 std::string SysWideToNativeMB(const std::wstring& wide) {
   return WideToUTF8(wide);
 }