components/browser_context_keyed_service/browser_context_keyed_service.h

   1 // Copyright (c) 2012 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_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_H_
   6 #define COMPONENTS_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_H_
   7
   8 #include "components/browser_context_keyed_service/browser_context_keyed_service_export.h"
   9
  10 class BrowserContextKeyedServiceFactory;
  11
  12 // Base class for all BrowserContextKeyedServices to allow for correct
  13 // destruction order.
  14 //
  15 // Many services that hang off BrowserContext have a two-pass shutdown. Many
  16 // subsystems need a first pass shutdown phase where they drop references. Not
  17 // all services will need this, so there's a default implementation. Only once
  18 // every system has been given a chance to drop references do we start deleting
  19 // objects.
  20 class BROWSER_CONTEXT_KEYED_SERVICE_EXPORT BrowserContextKeyedService {
  21  public:
  22   // The first pass is to call Shutdown on a BrowserContextKeyedService.
  23   virtual void Shutdown() {}
  24
  25  protected:
  26   friend class BrowserContextKeyedServiceFactory;
  27
  28   // The second pass is the actual deletion of each object.
  29   virtual ~BrowserContextKeyedService() {}
  30 };
  31
  32 #endif  // COMPONENTS_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_H_