Pass u2f message callback vector as a const reference

device/u2f/u2f_sign.h

Index: device/u2f/u2f_sign.h
diff --git a/device/u2f/u2f_sign.h b/device/u2f/u2f_sign.h
index e924137f81324e3a4d4ba05eafa602152379eac0..912fc77efa841d95b1f6d39bd283cf9e1a821d28 100644
--- a/device/u2f/u2f_sign.h
+++ b/device/u2f/u2f_sign.h
@@ -27,9 +27,9 @@ class U2fSign : public U2fRequest {
 
  private:
   void TryDevice() override;
-  void OnTryDevice(std::vector<std::vector<uint8_t>>::const_iterator,
-                   U2fReturnCode,
-                   std::vector<uint8_t>);
+  void OnTryDevice(std::vector<std::vector<uint8_t>>::const_iterator it,
+                   U2fReturnCode return_code,
+                   const std::vector<uint8_t>& response_data);
 
   const std::vector<std::vector<uint8_t>> registered_keys_;
   std::vector<uint8_t> challenge_hash_;