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

net/tools/quic/quic_simple_client.h

Index: net/tools/quic/quic_simple_client.h
diff --git a/net/tools/quic/quic_simple_client.h b/net/tools/quic/quic_simple_client.h
index 8c95ede1b2343369a2e0535f5f1eaef1bc853e0b..ce5c403cff86ffc416da37749515ff023398cae4 100644
--- a/net/tools/quic/quic_simple_client.h
+++ b/net/tools/quic/quic_simple_client.h
@@ -23,6 +23,7 @@
 #include "net/quic/chromium/quic_chromium_packet_reader.h"
 #include "net/quic/core/quic_config.h"
 #include "net/quic/core/quic_spdy_stream.h"
+#include "net/quic/platform/impl/quic_chromium_clock.h"
 #include "net/tools/quic/quic_client_base.h"
 
 namespace net {
@@ -83,7 +84,7 @@ class QuicSimpleClient : public QuicClientBase,
   void StartPacketReaderIfNotStarted();
 
   //  Used by |helper_| to time alarms.
-  QuicClock clock_;
+  QuicChromiumClock clock_;
 
   // Address of the client if the client is connected to the server.
   IPEndPoint client_address_;