Make UTF16ToASCII and UTF16TOUTF8 take a StringPiece

media/blink/webcontentdecryptionmodulesession_impl.cc

Index: media/blink/webcontentdecryptionmodulesession_impl.cc
diff --git a/media/blink/webcontentdecryptionmodulesession_impl.cc b/media/blink/webcontentdecryptionmodulesession_impl.cc
index 174ef5079c153be21e325ca467a53787af234e51..b28d9a64f7f06afeca20bd7b047e945602fc7a4e 100644
--- a/media/blink/webcontentdecryptionmodulesession_impl.cc
+++ b/media/blink/webcontentdecryptionmodulesession_impl.cc
@@ -165,7 +165,8 @@ static bool SanitizeSessionId(const blink::WebString& session_id,
   if (!base::IsStringASCII(session_id))
     return false;
 
-  sanitized_session_id->assign(base::UTF16ToASCII(session_id));
+  sanitized_session_id->assign(
+      base::UTF16ToASCII(base::StringPiece16(session_id)));
   if (sanitized_session_id->length() > limits::kMaxSessionIdLength)
     return false;