Banish boilerplate. Profile-keyed API factory for extension API classes.

chrome/browser/extensions/api/profile_keyed_api_factory.h

Index: chrome/browser/extensions/api/profile_keyed_api_factory.h
diff --git a/chrome/browser/extensions/api/profile_keyed_api_factory.h b/chrome/browser/extensions/api/profile_keyed_api_factory.h
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+// Copyright (c) 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 CHROME_BROWSER_EXTENSIONS_API_PROFILE_KEYED_API_FACTORY_H_
+#define CHROME_BROWSER_EXTENSIONS_API_PROFILE_KEYED_API_FACTORY_H_
+
+#include "chrome/browser/extensions/extension_system_factory.h"
+#include "chrome/browser/profiles/profile_dependency_manager.h"
+#include "chrome/browser/profiles/profile_keyed_service.h"
+#include "chrome/browser/profiles/profile_keyed_service_factory.h"
+
+namespace extensions {
+
+// Instantiations of ProfileKeyedAPIFactory should use this base class
+// and also define a static const char* service_name() function (used in the
+// ProfileKeyedBaseFactory constructor). These fields should be accessible
+// to the ProfileKeyedAPIFactory for the service.
+class ProfileKeyedAPI : public ProfileKeyedService {
+ protected:
+  // Defaults for flags that control ProfileKeyedAPIFactory behavior.
+  // See ProfileKeyedBaseFactory for usage.
+  static const bool kServiceRedirectedInIncognito = false;
+  static const bool kServiceIsNULLWhileTesting = false;
+};
+
+// A template for factories for ProfileKeyedServices that manage extension APIs.
+// T is a ProfileKeyedService that uses this factory template instead of
+// its own separate factory definition to manage its per-profile instances.
+template <typename T>
+class ProfileKeyedAPIFactory : public ProfileKeyedServiceFactory {
+ public:
+  static T* GetForProfile(Profile* profile) {
+    return static_cast<T*>(
+        GetInstance()->GetServiceForProfile(profile, true));
+  }
+
+  // Users of this factory template must manage their own instances
+  // (typically using LazyInstance or Singleton), because those cannot be
+  // included in more than one translation unit (and thus cannot be initialized
+  // in a header file).
+  //
+  // In the header file, declare the specialization, e.g.:
+  //   template <>
+  //   ProfileKeyedAPIFactory<ProcessesAPI>
+  //   ProfileKeyedAPIFactory<ProcessesAPI>::GetInstance();
+  //
+  // In the cc file, provide the implementation:
+  //   static base::LazyInstance<ProfileKeyedAPIFactory<ProcessesAPI> >
+  //   g_factory = LAZY_INSTANCE_INITIALIZER;
+  //
+  //   template <>
+  //   ProfileKeyedAPIFactory<ProcessesAPI>*
+  //   ProfileKeyedAPIFactory<ProcessesAPI>::GetInstance() {
+  //     return &g_factory.Get();
+  //   }
+
+  static ProfileKeyedAPIFactory* GetInstance();
+
+  // Declare dependencies on other factories.
+  // By default, ExtensionSystemFactory is the only dependency; however,
+  // specializations can override this. Declare your specialization in
+  // your header file after the ProfileKeyedAPI class definition.
+  // Then in the cc file (or inline in the header), define it, e.g.:
+  //   template <>
+  //   ProfileKeyedAPIFactory<PushMessagingAPI>::DeclareFactoryDependencies() {
+  //     DependsOn(ExtensionSystemFactory::GetInstance());
+  //     DependsOn(ProfileSyncServiceFactory::GetInstance());
+  // }
+  void DeclareFactoryDependencies() {
+    DependsOn(ExtensionSystemFactory::GetInstance());
+  }
+
+  ProfileKeyedAPIFactory()
+  : ProfileKeyedServiceFactory(T::service_name(),
+                               ProfileDependencyManager::GetInstance()) {
+    DeclareFactoryDependencies();
+  }
+
+  virtual ~ProfileKeyedAPIFactory() {
+  }
+
+ private:
+  // ProfileKeyedServiceFactory implementation.
+  virtual ProfileKeyedService* BuildServiceInstanceFor(
+      Profile* profile) const OVERRIDE {
+    return new T(profile);
+  }
+
+  // ProfileKeyedBaseFactory implementation.
+  // These can be effectively overridden with template specializations.
+  virtual bool ServiceRedirectedInIncognito() const OVERRIDE {
+    return T::kServiceRedirectedInIncognito;
+  }
+
+  virtual bool ServiceIsCreatedWithProfile() const OVERRIDE {
+    return true;
+  }
+
+  virtual bool ServiceIsNULLWhileTesting() const OVERRIDE {
+    return T::kServiceIsNULLWhileTesting;
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(ProfileKeyedAPIFactory);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_PROFILE_KEYED_API_FACTORY_H_