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

components/sync_driver/glue/sync_backend_host.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 COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 #define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 213 matching lines @@
 
   // Triggers sync cycle to update |types|.
   virtual void RefreshTypesForTest(syncer::ModelTypeSet types) = 0;
 
   // See SyncManager::ClearServerData.
   virtual void ClearServerData(
       const syncer::SyncManager::ClearServerDataCallback& callback) = 0;
 
   // Notify the syncer that the cookie jar has changed.
   // See SyncManager::OnCookieJarChanged.
-  virtual void OnCookieJarChanged(bool account_mismatch) = 0;
+  virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_