components/keyed_service/core/keyed_service.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_KEYED_SERVICE_CORE_KEYED_SERVICE_H_
   6 #define COMPONENTS_KEYED_SERVICE_CORE_KEYED_SERVICE_H_
   7
   8 #include "components/keyed_service/core/keyed_service_export.h"
   9
  10 // Interface for keyed services that support two-phase destruction order.
  11 //
  12 // Two-phase shutdown allows keyed services to have a first pass shutdown phase
  13 // where they drop references. Not all services will need this, so there's a
  14 // default implementation. Only once every service has been given a chance to
  15 // drop references are services deleted.
  16 class KEYED_SERVICE_EXPORT KeyedService {
  17  public:
  18   // The first pass is to call Shutdown on a KeyedService.
  19   virtual void Shutdown() {}
  20
  21   // The second pass is the actual deletion of each object.
  22   virtual ~KeyedService() {}
  23 };
  24
  25 #endif  // COMPONENTS_KEYED_SERVICE_CORE_KEYED_SERVICE_H_