Refactor sync-specific parts out of SyncNotifier/SyncNotifierObserver

sync/notifier/sync_notifier_observer.h

Index: sync/notifier/sync_notifier_observer.h
diff --git a/sync/notifier/sync_notifier_observer.h b/sync/notifier/sync_notifier_observer.h
index c4ac9ca5e63adc302d9a1ed83593448ab27ab9dd..f10597d2119668ee5e56a343694c08decac7e2ec 100644
--- a/sync/notifier/sync_notifier_observer.h
+++ b/sync/notifier/sync_notifier_observer.h
@@ -6,7 +6,7 @@
 #define SYNC_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_
 #pragma once
 
-#include "sync/internal_api/public/base/model_type_payload_map.h"
+#include "sync/notifier/object_id_payload_map.h"
 #include "sync/notifier/notifications_disabled_reason.h"
 
 namespace syncer {
@@ -20,6 +20,10 @@ enum IncomingNotificationSource {
 
 class SyncNotifierObserver {
  public:
+  // Returns the object IDs for which this observer would like to receive
+  // invalidation notifications.
+  virtual ObjectIdSet GetHandledIds() = 0;
+
   // Called when notifications are enabled.
   virtual void OnNotificationsEnabled() = 0;
 
@@ -28,10 +32,10 @@ class SyncNotifierObserver {
   virtual void OnNotificationsDisabled(
       NotificationsDisabledReason reason) = 0;
 
-  // Called when a notification is received.  The per-type payloads
+  // Called when a notification is received.  The per-id payloads
   // are in |type_payloads| and the source is in |source|.
   virtual void OnIncomingNotification(
-      const syncer::ModelTypePayloadMap& type_payloads,
+      const ObjectIdPayloadMap& id_payloads,
       IncomingNotificationSource source) = 0;
 
  protected: