extensions/browser/browser_context_keyed_api_factory.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 EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
   6 #define EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_
   7
   8 #include "components/keyed_service/content/browser_context_dependency_manager.h"
   9 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
  10 #include "components/keyed_service/core/keyed_service.h"
  11 #include "extensions/browser/extension_system_provider.h"
  12 #include "extensions/browser/extensions_browser_client.h"
  13
  14 namespace extensions {
  15
  16 template <typename T>
  17 class BrowserContextKeyedAPIFactory;
  18
  19 // Instantiations of BrowserContextKeyedAPIFactory should use this base class
  20 // and also define a static const char* service_name() function (used in the
  21 // BrowserContextKeyedBaseFactory constructor). These fields should
  22 // be accessible to the BrowserContextKeyedAPIFactory for the service.
  23 class BrowserContextKeyedAPI : public KeyedService {
  24  protected:
  25   // Defaults for flags that control BrowserContextKeyedAPIFactory behavior.
  26   // These can be overridden by subclasses to change that behavior.
  27   // See BrowserContextKeyedBaseFactory for usage.
  28
  29   // These flags affect what instance is returned when Get() is called
  30   // on an incognito profile. By default, it returns NULL. If
  31   // kServiceRedirectedInIncognito is true, it returns the instance for the
  32   // corresponding regular profile. If kServiceHasOwnInstanceInIncognito
  33   // is true, it returns a separate instance.
  34   static const bool kServiceRedirectedInIncognito = false;
  35   static const bool kServiceHasOwnInstanceInIncognito = false;
  36
  37   // If set to false, don't start the service at BrowserContext creation time.
  38   // (The default differs from the BrowserContextKeyedBaseFactory default,
  39   // because historically, BrowserContextKeyedAPIs often do tasks at startup.)
  40   static const bool kServiceIsCreatedWithBrowserContext = true;
  41
  42   // If set to true, GetForProfile returns NULL for TestingBrowserContexts.
  43   static const bool kServiceIsNULLWhileTesting = false;
  44
  45   // Users of this factory template must define a GetFactoryInstance()
  46   // and manage their own instances (typically using LazyInstance or
  47   // Singleton), because those cannot be included in more than one
  48   // translation unit (and thus cannot be initialized in a header file).
  49   //
  50   // In the header file, declare GetFactoryInstance(), e.g.:
  51   //   class HistoryAPI {
  52   //   ...
  53   //    public:
  54   //     static BrowserContextKeyedAPIFactory<HistoryAPI>* GetFactoryInstance();
  55   //   };
  56   //
  57   // In the cc file, provide the implementation, e.g.:
  58   //   static base::LazyInstance<BrowserContextKeyedAPIFactory<HistoryAPI> >
  59   //   g_factory = LAZY_INSTANCE_INITIALIZER;
  60   //
  61   //   // static
  62   //   BrowserContextKeyedAPIFactory<HistoryAPI>*
  63   //   HistoryAPI::GetFactoryInstance() {
  64   //     return g_factory.Pointer();
  65   //   }
  66 };
  67
  68 // A template for factories for KeyedServices that manage extension APIs. T is
  69 // a KeyedService that uses this factory template instead of its own separate
  70 // factory definition to manage its per-profile instances.
  71 template <typename T>
  72 class BrowserContextKeyedAPIFactory : public BrowserContextKeyedServiceFactory {
  73  public:
  74   static T* Get(content::BrowserContext* context) {
  75     return static_cast<T*>(
  76         T::GetFactoryInstance()->GetServiceForBrowserContext(context, true));
  77   }
  78
  79   // Declare dependencies on other factories.
  80   // By default, ExtensionSystemFactory is the only dependency; however,
  81   // specializations can override this. Declare your specialization in
  82   // your header file after the BrowserContextKeyedAPI class definition.
  83   // Then in the cc file (or inline in the header), define it, e.g.:
  84   //   template <>
  85   //   void BrowserContextKeyedAPIFactory<
  86   //       PushMessagingAPI>::DeclareFactoryDependencies() {
  87   //     DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
  88   //     DependsOn(ProfileSyncServiceFactory::GetInstance());
  89   //   }
  90   void DeclareFactoryDependencies() {
  91     DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
  92   }
  93
  94   BrowserContextKeyedAPIFactory()
  95       : BrowserContextKeyedServiceFactory(
  96             T::service_name(),
  97             BrowserContextDependencyManager::GetInstance()) {
  98     DeclareFactoryDependencies();
  99   }
 100
 101   virtual ~BrowserContextKeyedAPIFactory() {}
 102
 103  private:
 104   // BrowserContextKeyedServiceFactory implementation.
 105   virtual KeyedService* BuildServiceInstanceFor(
 106       content::BrowserContext* context) const OVERRIDE {
 107     return new T(context);
 108   }
 109
 110   // BrowserContextKeyedBaseFactory implementation.
 111   // These can be effectively overridden with template specializations.
 112   virtual content::BrowserContext* GetBrowserContextToUse(
 113       content::BrowserContext* context) const OVERRIDE {
 114     if (T::kServiceRedirectedInIncognito)
 115       return ExtensionsBrowserClient::Get()->GetOriginalContext(context);
 116
 117     if (T::kServiceHasOwnInstanceInIncognito)
 118       return context;
 119
 120     return BrowserContextKeyedServiceFactory::GetBrowserContextToUse(context);
 121   }
 122
 123   virtual bool ServiceIsCreatedWithBrowserContext() const OVERRIDE {
 124     return T::kServiceIsCreatedWithBrowserContext;
 125   }
 126
 127   virtual bool ServiceIsNULLWhileTesting() const OVERRIDE {
 128     return T::kServiceIsNULLWhileTesting;
 129   }
 130
 131   DISALLOW_COPY_AND_ASSIGN(BrowserContextKeyedAPIFactory);
 132 };
 133
 134 }  // namespace extensions
 135
 136 #endif  // EXTENSIONS_BROWSER_BROWSER_CONTEXT_KEYED_API_FACTORY_H_