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

net/quic/quartc/quartc_factory.h

Index: net/quic/quartc/quartc_factory.h
diff --git a/net/quic/quartc/quartc_factory.h b/net/quic/quartc/quartc_factory.h
index 056c3abf9373657933047f9ca97e88e08f46d679..e56d1655a903be24441b0b6bc3c71d9990e833f2 100644
--- a/net/quic/quartc/quartc_factory.h
+++ b/net/quic/quartc/quartc_factory.h
@@ -11,7 +11,7 @@
 #include "net/quic/core/quic_alarm_factory.h"
 #include "net/quic/core/quic_connection.h"
 #include "net/quic/core/quic_simple_buffer_allocator.h"
-#include "net/quic/platform/api/quic_clock.h"
+#include "net/quic/platform/impl/quic_chromium_clock.h"
 #include "net/quic/quartc/quartc_alarm_factory.h"
 #include "net/quic/quartc/quartc_factory_interface.h"
 #include "net/quic/quartc/quartc_packet_writer.h"
@@ -56,7 +56,7 @@ class NET_EXPORT_PRIVATE QuartcFactory : public QuartcFactoryInterface,
   // Used to implement QuicAlarmFactory..
   std::unique_ptr<QuartcTaskRunnerInterface> task_runner_;
   // Used to implement the QuicConnectionHelperInterface.
-  QuicClock clock_;
+  QuicChromiumClock clock_;
   SimpleBufferAllocator buffer_allocator_;
   // An AtExitManager owned by the QuartcFactory to manage the lifetime of
   // Singletons.