[Autofill] Run autofill-profile de-dupe after sync starts if sync is enabled.

components/autofill/core/browser/webdata/autofill_webdata_backend.h

 // Copyright 2013 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 COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_
 #define COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_
 
+#include "sync/internal_api/public/base/model_type.h"
+
 class WebDatabase;
 
 namespace autofill {
 
 class AutofillWebDataServiceObserverOnDBThread;
 
 // Interface for doing Autofill work directly on the DB thread (used by
 // Sync, mostly), without fully exposing the AutofillWebDataBackend to clients.
 class AutofillWebDataBackend {
  public:
@@ skipping 11 matching lines @@
       AutofillWebDataServiceObserverOnDBThread* observer) = 0;
 
   // Remove expired elements from the database and commit if needed.
   virtual void RemoveExpiredFormElements() = 0;
 
   // Notifies listeners on both DB and UI threads that multiple changes have
   // been made to to Autofill records of the database.
   // NOTE: This method is intended to be called from the DB thread. The UI
   // thread notifications are asynchronous.
   virtual void NotifyOfMultipleAutofillChanges() = 0;
+
+  // Notifies listeners on both DB and UI threads that sync has started for

[Mathieu, 2016/07/18 14:53:19]

Not sure I see how DB thread observers are notified?

[Roger McFarlane (Chromium), 2016/07/18 15:29:18]

Copy-paste error, fixed.

+  // |model_type|.
+  virtual void NotifyThatSyncHasStarted(syncer::ModelType model_type) = 0;
 };
 
 } // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_