Create a ProfileDependencyManager to order ProfileKeyedService destruction.

chrome/browser/profiles/profile_dependency_manager.h

+// Copyright (c) 2011 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 CHROME_BROWSER_PROFILES_PROFILE_DEPENDENCY_MANAGER_H_
+#define CHROME_BROWSER_PROFILES_PROFILE_DEPENDENCY_MANAGER_H_
+
+#include <map>
+#include <vector>
+
+#include "base/memory/singleton.h"
+
+class Profile;
+class ProfileKeyedServiceFactory;
+
+// A singleton that listens for profile destruction notifications and
+// rebroadcasts them to each ProfileKeyedServiceFactory in a safe order based
+// on the stated dependencies by each service.
+class ProfileDependencyManager {
+ public:
+  // Adds/Removes a component from our list of live components. Removing will
+  // also remove live dependency links.
+  void AddComponent(ProfileKeyedServiceFactory* component);
+  void RemoveComponent(ProfileKeyedServiceFactory* component);
+
+  // Adds a dependency between two factories.
+  void AddEdge(ProfileKeyedServiceFactory* depended,
+               ProfileKeyedServiceFactory* dependee);
+
+  // Called by each Profile to alert us that we should destroy services
+  // associated with it.
+  //
+  // Why not use the existing PROFILE_DESTROYED notification?
+  //
+  // - Because we need to do everything here after the application has handled
+  //   being notified about PROFILE_DESTROYED.
+  // - Because this class is a singleton and Singletons can't rely on
+  //   NotificationService in unit tests because NotificationService is
+  //   replaced in many tests.
+  void DestroyProfileServices(Profile* profile);
+
+  static ProfileDependencyManager* GetInstance();
+
+ private:
+  friend class ProfileDependencyManagerUnittests;
+  friend struct DefaultSingletonTraits<ProfileDependencyManager>;
+
+  typedef std::multimap<ProfileKeyedServiceFactory*,
+                        ProfileKeyedServiceFactory*> EdgeMap;
+
+  ProfileDependencyManager();
+  virtual ~ProfileDependencyManager();
+
+  // Using the dependency graph defined in |edges_|, fills |destruction_order_|
+  // so that Observe() can notify each ProfileKeyedServiceFactory in order.
+  void BuildDestructionOrder();
+
+  std::vector<ProfileKeyedServiceFactory*> all_components_;
+
+  EdgeMap edges_;
+
+  std::vector<ProfileKeyedServiceFactory*> destruction_order_;
+};
+
+#endif  // CHROME_BROWSER_PROFILES_PROFILE_DEPENDENCY_MANAGER_H_