FilePath: add a convertor to ASCII

base/file_path.cc

Index: base/file_path.cc
diff --git a/base/file_path.cc b/base/file_path.cc
index 5f1375adb5b8e9c98942bc69a474a8761d7682bb..907a4124b6a428845565a5f51aa687506c3b7bb3 100644
--- a/base/file_path.cc
+++ b/base/file_path.cc
@@ -520,6 +520,12 @@ string16 FilePath::LossyDisplayName() const {
   return WideToUTF16(base::SysNativeMBToWide(path_));
 }
 
+std::string FilePath::MaybeAsASCII() const {
+  if (IsStringASCII(path_))
+    return path_;
+  return "";
+}
+
 // The *Hack functions are temporary while we fix the remainder of the code.
 // Remember to remove the #includes at the top when you remove these.
 
@@ -535,6 +541,12 @@ string16 FilePath::LossyDisplayName() const {
   return path_;
 }
 
+std::string FilePath::MaybeAsASCII() const {
+  if (IsStringASCII(path_))
+    return WideToASCII(path_);
+  return "";
+}
+
 // static
 FilePath FilePath::FromWStringHack(const std::wstring& wstring) {
   return FilePath(wstring);