wstrings: make l10n_util::TruncateString use string16

app/l10n_util.h

Index: app/l10n_util.h
diff --git a/app/l10n_util.h b/app/l10n_util.h
index 54328e781b50c42a9aa2bf1d4a5a9d40858903ad..a1519b58e717c7024bc066c70996d3a01c396e1b 100644
--- a/app/l10n_util.h
+++ b/app/l10n_util.h
@@ -163,7 +163,7 @@ std::wstring GetStringF(int message_id, int64 a);
 // character (unicode character 0x2026) to render ...
 // The supplied string is returned if the string has length characters or
 // less.
-std::wstring TruncateString(const std::wstring& string, size_t length);
+string16 TruncateString(const string16& string, size_t length);
 
 // Returns the lower case equivalent of string.
 string16 ToLower(const string16& string);