Add a QuicChromiumClock and make QuicClock abstract to match internal code.

net/quic/quartc/quartc_session.h

Index: net/quic/quartc/quartc_session.h
diff --git a/net/quic/quartc/quartc_session.h b/net/quic/quartc/quartc_session.h
index a27e4558bf36b3900ba5ff1ca6fb00480f5f5237..bcbff25c3b53dcc9597bb2845c57d06c0fef49f1 100644
--- a/net/quic/quartc/quartc_session.h
+++ b/net/quic/quartc/quartc_session.h
@@ -10,6 +10,7 @@
 #include "net/quic/core/quic_crypto_server_stream.h"
 #include "net/quic/core/quic_crypto_stream.h"
 #include "net/quic/core/quic_session.h"
+#include "net/quic/platform/impl/quic_chromium_clock.h"
 #include "net/quic/quartc/quartc_session_interface.h"
 #include "net/quic/quartc/quartc_stream.h"
 
@@ -97,7 +98,7 @@ class NET_EXPORT_PRIVATE QuartcSession
   // For crypto handshake.
   std::unique_ptr<QuicCryptoStream> crypto_stream_;
   // For recording packet receipt time
-  QuicClock clock_;
+  QuicChromiumClock clock_;
   const std::string unique_remote_server_id_;
   Perspective perspective_;
   // Take the ownership of the QuicConnection.