[Sync] Add histograms for cookie jar state on Sessions commit

sync/internal_api/public/sync_manager.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_INTERNAL_API_PUBLIC_SYNC_MANAGER_H_
 #define SYNC_INTERNAL_API_PUBLIC_SYNC_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 391 matching lines @@
   // Clears server data and invokes |callback| when complete.
   //
   // This is an asynchronous operation that requires interaction with the sync
   // server. The operation will automatically be retried with backoff until it
   // completes successfully or sync is shutdown.
   virtual void ClearServerData(const ClearServerDataCallback& callback) = 0;
 
   // Updates Sync's tracking of whether the cookie jar has a mismatch with the
   // chrome account. See ClientConfigParams proto message for more info.
   // Note: this does not trigger a sync cycle. It just updates the sync context.
-  virtual void OnCookieJarChanged(bool account_mismatch) = 0;
+  virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_SYNC_MANAGER_H_