diff --git a/quic/quartc/quartc_session.cc b/quic/quartc/quartc_session.cc
index 2e6729c..95c7e86 100644
--- a/quic/quartc/quartc_session.cc
+++ b/quic/quartc/quartc_session.cc
@@ -246,7 +246,8 @@
   session_delegate_->OnMessageReceived(message);
 }
 
-void QuartcSession::OnMessageAcked(QuicMessageId message_id) {
+void QuartcSession::OnMessageAcked(QuicMessageId message_id,
+                                   QuicTime receive_timestamp) {
   auto element = message_to_datagram_id_.find(message_id);
 
   if (element == message_to_datagram_id_.end()) {
@@ -255,6 +256,7 @@
     return;
   }
 
+  // TODO(mellem): Pass receive_timestamp to |delegate_|.
   session_delegate_->OnMessageAcked(/*datagram_id=*/element->second);
 
   // Free up space -- we should never see message_id again.
diff --git a/quic/quartc/quartc_session.h b/quic/quartc/quartc_session.h
index 042827b..cd8d2cb 100644
--- a/quic/quartc/quartc_session.h
+++ b/quic/quartc/quartc_session.h
@@ -176,7 +176,8 @@
   void OnMessageReceived(QuicStringPiece message) override;
 
   // Called when message with |message_id| gets acked.
-  void OnMessageAcked(QuicMessageId message_id) override;
+  void OnMessageAcked(QuicMessageId message_id,
+                      QuicTime receive_timestamp) override;
 
   // Returns number of queued (not sent) messages submitted by
   // SendOrQueueMessage. Messages are queued if connection is congestion