Added nudge source counters to about:sync.

sync/internal_api/public/engine/sync_status.h

Index: sync/internal_api/public/engine/sync_status.h
diff --git a/sync/internal_api/public/engine/sync_status.h b/sync/internal_api/public/engine/sync_status.h
index 3b9229fb39c9c0487a67a04982142c735b80677b..af77741778ca940f31e5c4405f1ee2a6b33ec394 100644
--- a/sync/internal_api/public/engine/sync_status.h
+++ b/sync/internal_api/public/engine/sync_status.h
@@ -81,6 +81,13 @@ struct SYNC_EXPORT SyncStatus {
   int useless_sync_cycles;
   int useful_sync_cycles;
 
+  // Nudge counts for each possible source
+  int nudge_source_unknown;
+  int nudge_source_notification;
+  int nudge_source_local;
+  int nudge_source_continuation;
+  int nudge_source_local_refresh;
+
   // Encryption related.
   ModelTypeSet encrypted_types;
   bool cryptographer_ready;