[Sync] Turn notifier::PushClient into an interface

sync/notifier/sync_notifier_factory.cc

Index: sync/notifier/sync_notifier_factory.cc
diff --git a/sync/notifier/sync_notifier_factory.cc b/sync/notifier/sync_notifier_factory.cc
index 5c864f7afcce095feaae7adf9c163aae80623da0..ed838b12407160e5f6776a692f1ac213e25debcc 100644
--- a/sync/notifier/sync_notifier_factory.cc
+++ b/sync/notifier/sync_notifier_factory.cc
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "base/logging.h"
+#include "jingle/notifier/listener/push_client.h"
 #include "sync/notifier/non_blocking_invalidation_notifier.h"
 #include "sync/notifier/p2p_notifier.h"
 #include "sync/notifier/sync_notifier.h"
@@ -25,7 +26,9 @@ SyncNotifier* CreateDefaultSyncNotifier(
     // NOTIFY_OTHERS.  There's no good reason to notify ourselves of our own
     // commits.  We self-notify for now only because the integration tests rely
     // on this behaviour.  See crbug.com/97780.
-    return new P2PNotifier(notifier_options, NOTIFY_ALL);
+    return new P2PNotifier(
+        notifier::PushClient::CreateDefault(notifier_options),
+        NOTIFY_ALL);
   }
 
   return new NonBlockingInvalidationNotifier(