sync: Per-type update application

sync/engine/sync_engine_event.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SYNC_ENGINE_SYNC_ENGINE_EVENT_H_
 #define SYNC_ENGINE_SYNC_ENGINE_EVENT_H_
 
 #include <string>
 
 #include "base/observer_list.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/sessions/sync_session_snapshot.h"
 
 namespace syncable {
 class Id;
 }
 
 namespace syncer {
 
 struct SYNC_EXPORT_PRIVATE SyncEngineEvent {
   enum EventCause {
     ////////////////////////////////////////////////////////////////
     // Sent on entry of Syncer state machine
     SYNC_CYCLE_BEGIN,
 
-    // SyncerCommand generated events.
+    // Sent any time progress is made during a sync cycle.
     STATUS_CHANGED,
 
     // We have reached the SYNCER_END state in the main sync loop.
     SYNC_CYCLE_ENDED,
 
     ////////////////////////////////////////////////////////////////
     // Generated in response to specific protocol actions or events.
 
     // This is sent after the Syncer (and SyncerThread) have initiated self
     // halt due to no longer being permitted to communicate with the server.
@@ skipping 37 matching lines @@
   // TODO(tim): Consider splitting this up to multiple callbacks, rather than
   // have to do Event e(type); OnSyncEngineEvent(e); at all callsites,
   virtual void OnSyncEngineEvent(const SyncEngineEvent& event) = 0;
  protected:
   virtual ~SyncEngineEventListener() {}
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_ENGINE_EVENT_H_