Extract EventRouter from ExtensionSystem.

This patch removes event_router accessor from ExtensionSystem.
EventRouter is now a browser context keyed service.

BUG=496281

Review URL: https://codereview.chromium.org/1148983004

Cr-Commit-Position: refs/heads/master@{#332745}

21 files changed, 161 insertions, 128 deletions

diff --git a/extensions/browser/api/app_runtime/app_runtime_api.cc b/extensions/browser/api/app_runtime/app_runtime_api.cc
index fba27b9..e606dbc 100644
--- a/extensions/browser/api/app_runtime/app_runtime_api.cc
+++ b/extensions/browser/api/app_runtime/app_runtime_api.cc
@@ -9,7 +9,6 @@
 #include "base/values.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_prefs.h"
-#include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/granted_file_entry.h"
 #include "extensions/common/api/app_runtime.h"
@@ -31,12 +30,11 @@ void DispatchOnEmbedRequestedEventImpl(
     content::BrowserContext* context) {
   scoped_ptr<base::ListValue> args(new base::ListValue());
   args->Append(app_embedding_request_data.release());
-  ExtensionSystem* system = ExtensionSystem::Get(context);
   scoped_ptr<Event> event(
       new Event(app_runtime::OnEmbedRequested::kEventName, args.Pass()));
   event->restrict_to_browser_context = context;
-  system->event_router()->DispatchEventWithLazyListener(extension_id,
-                                                        event.Pass());
+  EventRouter::Get(context)
+      ->DispatchEventWithLazyListener(extension_id, event.Pass());
 
   ExtensionPrefs::Get(context)
       ->SetLastLaunchTime(extension_id, base::Time::Now());
diff --git a/extensions/browser/api/runtime/runtime_api.cc b/extensions/browser/api/runtime/runtime_api.cc
index 6e23721..72dacf7 100644
--- a/extensions/browser/api/runtime/runtime_api.cc
+++ b/extensions/browser/api/runtime/runtime_api.cc
@@ -107,7 +107,8 @@ void DispatchOnStartupEventImpl(BrowserContext* browser_context,
   scoped_ptr<base::ListValue> event_args(new base::ListValue());
   scoped_ptr<Event> event(
       new Event(runtime::OnStartup::kEventName, event_args.Pass()));
-  system->event_router()->DispatchEventToExtension(extension_id, event.Pass());
+  EventRouter::Get(browser_context)
+      ->DispatchEventToExtension(extension_id, event.Pass());
 }
 
 void SetUninstallURL(ExtensionPrefs* prefs,
@@ -304,11 +305,11 @@ void RuntimeEventRouter::DispatchOnInstalledEvent(
   } else {
     info->SetString(kInstallReason, kInstallReasonInstall);
   }
-  DCHECK(system->event_router());
+  EventRouter* event_router = EventRouter::Get(context);
+  DCHECK(event_router);
   scoped_ptr<Event> event(
       new Event(runtime::OnInstalled::kEventName, event_args.Pass()));
-  system->event_router()->DispatchEventWithLazyListener(extension_id,
-                                                        event.Pass());
+  event_router->DispatchEventWithLazyListener(extension_id, event.Pass());
 
   if (old_version.IsValid()) {
     const Extension* extension =
@@ -328,8 +329,8 @@ void RuntimeEventRouter::DispatchOnInstalledEvent(
         sm_info->SetString(kInstallId, extension_id);
         scoped_ptr<Event> sm_event(
             new Event(runtime::OnInstalled::kEventName, sm_event_args.Pass()));
-        system->event_router()->DispatchEventWithLazyListener((*i)->id(),
-                                                              sm_event.Pass());
+        event_router->DispatchEventWithLazyListener((*i)->id(),
+                                                    sm_event.Pass());
       }
     }
   }
@@ -346,10 +347,11 @@ void RuntimeEventRouter::DispatchOnUpdateAvailableEvent(
 
   scoped_ptr<base::ListValue> args(new base::ListValue);
   args->Append(manifest->DeepCopy());
-  DCHECK(system->event_router());
+  EventRouter* event_router = EventRouter::Get(context);
+  DCHECK(event_router);
   scoped_ptr<Event> event(
       new Event(runtime::OnUpdateAvailable::kEventName, args.Pass()));
-  system->event_router()->DispatchEventToExtension(extension_id, event.Pass());
+  event_router->DispatchEventToExtension(extension_id, event.Pass());
 }
 
 // static
@@ -360,10 +362,11 @@ void RuntimeEventRouter::DispatchOnBrowserUpdateAvailableEvent(
     return;
 
   scoped_ptr<base::ListValue> args(new base::ListValue);
-  DCHECK(system->event_router());
+  EventRouter* event_router = EventRouter::Get(context);
+  DCHECK(event_router);
   scoped_ptr<Event> event(
       new Event(runtime::OnBrowserUpdateAvailable::kEventName, args.Pass()));
-  system->event_router()->BroadcastEvent(event.Pass());
+  event_router->BroadcastEvent(event.Pass());
 }
 
 // static
@@ -378,9 +381,9 @@ void RuntimeEventRouter::DispatchOnRestartRequiredEvent(
   scoped_ptr<Event> event(
       new Event(runtime::OnRestartRequired::kEventName,
                 core_api::runtime::OnRestartRequired::Create(reason)));
-
-  DCHECK(system->event_router());
-  system->event_router()->DispatchEventToExtension(app_id, event.Pass());
+  EventRouter* event_router = EventRouter::Get(context);
+  DCHECK(event_router);
+  event_router->DispatchEventToExtension(app_id, event.Pass());
 }
 
 // static
diff --git a/extensions/browser/api/storage/settings_test_util.cc b/extensions/browser/api/storage/settings_test_util.cc
index b5142f0..c3dc4a5 100644
--- a/extensions/browser/api/storage/settings_test_util.cc
+++ b/extensions/browser/api/storage/settings_test_util.cc
@@ -118,27 +118,6 @@ scoped_refptr<const Extension> AddExtensionWithIdAndPermissions(
   return extension;
 }
 
-// MockExtensionSystemWithEventRouter
-
-MockExtensionSystemWithEventRouter::MockExtensionSystemWithEventRouter(
-    content::BrowserContext* context)
-    : MockExtensionSystem(context) {
-}
-
-MockExtensionSystemWithEventRouter::~MockExtensionSystemWithEventRouter() {
-}
-
-KeyedService* MockExtensionSystemWithEventRouter::Build(
-    content::BrowserContext* context) {
-  return new MockExtensionSystemWithEventRouter(context);
-}
-
-EventRouter* MockExtensionSystemWithEventRouter::event_router() {
-  if (!event_router_.get())
-    event_router_.reset(new EventRouter(browser_context(), NULL));
-  return event_router_.get();
-}
-
 // ScopedSettingsFactory
 
 ScopedSettingsStorageFactory::ScopedSettingsStorageFactory() {}
diff --git a/extensions/browser/api/storage/settings_test_util.h b/extensions/browser/api/storage/settings_test_util.h
index 283fc46..0b23f60 100644
--- a/extensions/browser/api/storage/settings_test_util.h
+++ b/extensions/browser/api/storage/settings_test_util.h
@@ -56,25 +56,6 @@ scoped_refptr<const Extension> AddExtensionWithIdAndPermissions(
     Manifest::Type type,
     const std::set<std::string>& permissions);
 
-// A MockExtensionSystem to serve an EventRouter.
-// NOTE: New code should prefer using MockExtensionSystem directly.
-class MockExtensionSystemWithEventRouter : public MockExtensionSystem {
- public:
-  explicit MockExtensionSystemWithEventRouter(content::BrowserContext* context);
-  ~MockExtensionSystemWithEventRouter() override;
-
-  // Factory method for SetTestingFactoryAndUse.
-  static KeyedService* Build(content::BrowserContext* context);
-
-  // MockExtensionSystem overrides:
-  EventRouter* event_router() override;
-
- private:
-  scoped_ptr<EventRouter> event_router_;
-
-  DISALLOW_COPY_AND_ASSIGN(MockExtensionSystemWithEventRouter);
-};
-
 // SettingsStorageFactory which acts as a wrapper for other factories.
 class ScopedSettingsStorageFactory : public SettingsStorageFactory {
  public:
diff --git a/extensions/browser/api/storage/storage_api_unittest.cc b/extensions/browser/api/storage/storage_api_unittest.cc
index a0845d9..0d2dc4d 100644
--- a/extensions/browser/api/storage/storage_api_unittest.cc
+++ b/extensions/browser/api/storage/storage_api_unittest.cc
@@ -15,9 +15,7 @@
 #include "extensions/browser/api/storage/storage_frontend.h"
 #include "extensions/browser/api_unittest.h"
 #include "extensions/browser/event_router.h"
-#include "extensions/browser/extension_prefs.h"
-#include "extensions/browser/extension_system.h"
-#include "extensions/browser/mock_extension_system.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/test_extensions_browser_client.h"
 #include "extensions/browser/value_store/leveldb_value_store.h"
 #include "extensions/browser/value_store/value_store.h"
@@ -37,6 +35,10 @@ KeyedService* CreateStorageFrontendForTesting(
                                            context);
 }
 
+KeyedService* BuildEventRouter(content::BrowserContext* profile) {
+  return new extensions::EventRouter(profile, nullptr);
+}
+
 }  // namespace
 
 class StorageApiUnittest : public ApiUnitTest {
@@ -76,10 +78,8 @@ class StorageApiUnittest : public ApiUnitTest {
 };
 
 TEST_F(StorageApiUnittest, RestoreCorruptedStorage) {
-  EventRouter event_router(browser_context(), nullptr);
-  MockExtensionSystem* system = static_cast<MockExtensionSystem*>(
-      ExtensionSystem::Get(browser_context()));
-  system->set_event_router(&event_router);
+  EventRouterFactory::GetInstance()->SetTestingFactory(browser_context(),
+                                                       &BuildEventRouter);
 
   // Ensure a StorageFrontend can be created on demand. The StorageFrontend
   // will be owned by the KeyedService system.
diff --git a/extensions/browser/browser_context_keyed_service_factories.cc b/extensions/browser/browser_context_keyed_service_factories.cc
index 3eb3106..ee2a901 100644
--- a/extensions/browser/browser_context_keyed_service_factories.cc
+++ b/extensions/browser/browser_context_keyed_service_factories.cc
@@ -27,6 +27,7 @@
 #include "extensions/browser/api/usb/usb_guid_map.h"
 #include "extensions/browser/api/vpn_provider/vpn_service_factory.h"
 #include "extensions/browser/api/webcam_private/webcam_private_api.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_message_filter.h"
 #include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/process_manager_factory.h"
@@ -49,6 +50,7 @@ void EnsureBrowserContextKeyedServiceFactoriesBuilt() {
   core_api::TCPServerSocketEventDispatcher::GetFactoryInstance();
   core_api::TCPSocketEventDispatcher::GetFactoryInstance();
   core_api::UDPSocketEventDispatcher::GetFactoryInstance();
+  EventRouterFactory::GetInstance();
   ExtensionMessageFilter::EnsureShutdownNotifierFactoryBuilt();
   ExtensionPrefsFactory::GetInstance();
   HidDeviceManager::GetFactoryInstance();
diff --git a/extensions/browser/event_router.cc b/extensions/browser/event_router.cc
index 6a8cf8d..71a0963 100644
--- a/extensions/browser/event_router.cc
+++ b/extensions/browser/event_router.cc
@@ -16,6 +16,7 @@
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 #include "extensions/browser/api_activity_monitor.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
@@ -136,7 +137,7 @@ void EventRouter::DispatchExtensionMessage(IPC::Sender* ipc_sender,
 
 // static
 EventRouter* EventRouter::Get(content::BrowserContext* browser_context) {
-  return ExtensionSystem::Get(browser_context)->event_router();
+  return EventRouterFactory::GetForBrowserContext(browser_context);
 }
 
 // static
diff --git a/extensions/browser/event_router.h b/extensions/browser/event_router.h
index aec74ed..6cd7df6 100644
--- a/extensions/browser/event_router.h
+++ b/extensions/browser/event_router.h
@@ -17,6 +17,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/scoped_observer.h"
 #include "base/values.h"
+#include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/render_process_host_observer.h"
@@ -44,7 +45,8 @@ struct Event;
 struct EventDispatchInfo;
 struct EventListenerInfo;
 
-class EventRouter : public content::NotificationObserver,
+class EventRouter : public KeyedService,
+                    public content::NotificationObserver,
                     public ExtensionRegistryObserver,
                     public EventListenerMap::Delegate,
                     public content::RenderProcessHostObserver {
diff --git a/extensions/browser/event_router_factory.cc b/extensions/browser/event_router_factory.cc
new file mode 100644
index 0000000..9dd0125
--- /dev/null
+++ b/extensions/browser/event_router_factory.cc
@@ -0,0 +1,52 @@
+// Copyright 2015 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.
+
+#include "extensions/browser/event_router_factory.h"
+
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "content/public/browser/browser_context.h"
+#include "extensions/browser/event_router.h"
+#include "extensions/browser/extension_prefs.h"
+#include "extensions/browser/extension_prefs_factory.h"
+#include "extensions/browser/extension_registry_factory.h"
+#include "extensions/browser/extensions_browser_client.h"
+
+using content::BrowserContext;
+
+namespace extensions {
+
+// static
+EventRouter* EventRouterFactory::GetForBrowserContext(BrowserContext* context) {
+  return static_cast<EventRouter*>(
+      GetInstance()->GetServiceForBrowserContext(context, true));
+}
+
+// static
+EventRouterFactory* EventRouterFactory::GetInstance() {
+  return Singleton<EventRouterFactory>::get();
+}
+
+EventRouterFactory::EventRouterFactory()
+    : BrowserContextKeyedServiceFactory(
+          "EventRouter",
+          BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(ExtensionRegistryFactory::GetInstance());
+  DependsOn(ExtensionPrefsFactory::GetInstance());
+}
+
+EventRouterFactory::~EventRouterFactory() {
+}
+
+KeyedService* EventRouterFactory::BuildServiceInstanceFor(
+    BrowserContext* context) const {
+  return new EventRouter(context, ExtensionPrefs::Get(context));
+}
+
+BrowserContext* EventRouterFactory::GetBrowserContextToUse(
+    BrowserContext* context) const {
+  // Redirected in incognito.
+  return ExtensionsBrowserClient::Get()->GetOriginalContext(context);
+}
+
+}  // namespace extensions
diff --git a/extensions/browser/event_router_factory.h b/extensions/browser/event_router_factory.h
new file mode 100644
index 0000000..a2ba6ff
--- /dev/null
+++ b/extensions/browser/event_router_factory.h
@@ -0,0 +1,37 @@
+// Copyright 2015 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 EXTENSIONS_BROWSER_EVENT_ROUTER_FACTORY_H_
+#define EXTENSIONS_BROWSER_EVENT_ROUTER_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace extensions {
+
+class EventRouter;
+
+class EventRouterFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static EventRouter* GetForBrowserContext(content::BrowserContext* context);
+  static EventRouterFactory* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<EventRouterFactory>;
+
+  EventRouterFactory();
+  ~EventRouterFactory() override;
+
+  // BrowserContextKeyedServiceFactory implementation
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(EventRouterFactory);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_EVENT_ROUTER_FACTORY_H_
diff --git a/extensions/browser/extension_message_filter.cc b/extensions/browser/extension_message_filter.cc
index 2a67822..053d8ee 100644
--- a/extensions/browser/extension_message_filter.cc
+++ b/extensions/browser/extension_message_filter.cc
@@ -11,9 +11,7 @@
 #include "content/public/browser/render_process_host.h"
 #include "extensions/browser/blob_holder.h"
 #include "extensions/browser/event_router.h"
-#include "extensions/browser/extension_system.h"
-#include "extensions/browser/extension_system_provider.h"
-#include "extensions/browser/extensions_browser_client.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/process_manager_factory.h"
 #include "extensions/common/extension.h"
@@ -40,7 +38,7 @@ class ShutdownNotifierFactory
   ShutdownNotifierFactory()
       : BrowserContextKeyedServiceShutdownNotifierFactory(
             "ExtensionMessageFilter") {
-    DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
+    DependsOn(EventRouterFactory::GetInstance());
     DependsOn(ProcessManagerFactory::GetInstance());
   }
   ~ShutdownNotifierFactory() override {}
@@ -54,7 +52,7 @@ ExtensionMessageFilter::ExtensionMessageFilter(int render_process_id,
                                                content::BrowserContext* context)
     : BrowserMessageFilter(ExtensionMsgStart),
       render_process_id_(render_process_id),
-      extension_system_(ExtensionSystem::Get(context)),
+      event_router_(EventRouter::Get(context)),
       process_manager_(ProcessManager::Get(context)) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   shutdown_notifier_ =
@@ -72,7 +70,7 @@ ExtensionMessageFilter::~ExtensionMessageFilter() {
 }
 
 void ExtensionMessageFilter::ShutdownOnUIThread() {
-  extension_system_ = nullptr;
+  event_router_ = nullptr;
   process_manager_ = nullptr;
   shutdown_notifier_.reset();
 }
@@ -103,7 +101,7 @@ void ExtensionMessageFilter::OnDestruct() const {
 
 bool ExtensionMessageFilter::OnMessageReceived(const IPC::Message& message) {
   // If we have been shut down already, return.
-  if (!extension_system_)
+  if (!event_router_)
     return true;
 
   bool handled = true;
@@ -139,14 +137,13 @@ void ExtensionMessageFilter::OnExtensionAddListener(
   if (!process)
     return;
 
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
   if (crx_file::id_util::IdIsValid(extension_id)) {
-    router->AddEventListener(event_name, process, extension_id);
+    event_router_->AddEventListener(event_name, process, extension_id);
   } else if (listener_url.is_valid()) {
-    router->AddEventListenerForURL(event_name, process, listener_url);
+    event_router_->AddEventListenerForURL(event_name, process, listener_url);
   } else {
     NOTREACHED() << "Tried to add an event listener without a valid "
                  << "extension ID nor listener URL";
@@ -161,14 +158,13 @@ void ExtensionMessageFilter::OnExtensionRemoveListener(
   if (!process)
     return;
 
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
   if (crx_file::id_util::IdIsValid(extension_id)) {
-    router->RemoveEventListener(event_name, process, extension_id);
+    event_router_->RemoveEventListener(event_name, process, extension_id);
   } else if (listener_url.is_valid()) {
-    router->RemoveEventListenerForURL(event_name, process, listener_url);
+    event_router_->RemoveEventListenerForURL(event_name, process, listener_url);
   } else {
     NOTREACHED() << "Tried to remove an event listener without a valid "
                  << "extension ID nor listener URL";
@@ -177,20 +173,18 @@ void ExtensionMessageFilter::OnExtensionRemoveListener(
 
 void ExtensionMessageFilter::OnExtensionAddLazyListener(
     const std::string& extension_id, const std::string& event_name) {
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
-  router->AddLazyEventListener(event_name, extension_id);
+  event_router_->AddLazyEventListener(event_name, extension_id);
 }
 
 void ExtensionMessageFilter::OnExtensionRemoveLazyListener(
     const std::string& extension_id, const std::string& event_name) {
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
-  router->RemoveLazyEventListener(event_name, extension_id);
+  event_router_->RemoveLazyEventListener(event_name, extension_id);
 }
 
 void ExtensionMessageFilter::OnExtensionAddFilteredListener(
@@ -202,12 +196,11 @@ void ExtensionMessageFilter::OnExtensionAddFilteredListener(
   if (!process)
     return;
 
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
-  router->AddFilteredEventListener(
-      event_name, process, extension_id, filter, lazy);
+  event_router_->AddFilteredEventListener(event_name, process, extension_id,
+                                          filter, lazy);
 }
 
 void ExtensionMessageFilter::OnExtensionRemoveFilteredListener(
@@ -219,12 +212,11 @@ void ExtensionMessageFilter::OnExtensionRemoveFilteredListener(
   if (!process)
     return;
 
-  EventRouter* router = extension_system_->event_router();
-  if (!router)
+  if (!event_router_)
     return;
 
-  router->RemoveFilteredEventListener(
-      event_name, process, extension_id, filter, lazy);
+  event_router_->RemoveFilteredEventListener(event_name, process, extension_id,
+                                             filter, lazy);
 }
 
 void ExtensionMessageFilter::OnExtensionShouldSuspendAck(
diff --git a/extensions/browser/extension_message_filter.h b/extensions/browser/extension_message_filter.h
index b54596e..e0c0e0c 100644
--- a/extensions/browser/extension_message_filter.h
+++ b/extensions/browser/extension_message_filter.h
@@ -26,7 +26,7 @@ class Size;
 
 namespace extensions {
 
-class ExtensionSystem;
+class EventRouter;
 class ProcessManager;
 
 // This class filters out incoming extension-specific IPC messages from the
@@ -84,7 +84,7 @@ class ExtensionMessageFilter : public content::BrowserMessageFilter {
   scoped_ptr<KeyedServiceShutdownNotifier::Subscription> shutdown_notifier_;
 
   // Owned by the browser context; should only be accessed on the UI thread.
-  ExtensionSystem* extension_system_;
+  EventRouter* event_router_;
   ProcessManager* process_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionMessageFilter);
diff --git a/extensions/browser/extension_pref_value_map_factory.cc b/extensions/browser/extension_pref_value_map_factory.cc
index 6ce78e8..10fdf09 100644
--- a/extensions/browser/extension_pref_value_map_factory.cc
+++ b/extensions/browser/extension_pref_value_map_factory.cc
@@ -6,6 +6,7 @@
 
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/extension_pref_value_map.h"
+#include "extensions/browser/extensions_browser_client.h"
 
 ExtensionPrefValueMapFactory::ExtensionPrefValueMapFactory()
     : BrowserContextKeyedServiceFactory(
@@ -32,3 +33,10 @@ KeyedService* ExtensionPrefValueMapFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   return new ExtensionPrefValueMap();
 }
+
+content::BrowserContext* ExtensionPrefValueMapFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  // Redirected in incognito.
+  return extensions::ExtensionsBrowserClient::Get()->GetOriginalContext(
+      context);
+}
diff --git a/extensions/browser/extension_pref_value_map_factory.h b/extensions/browser/extension_pref_value_map_factory.h
index c2630f0..cbe7d5a 100644
--- a/extensions/browser/extension_pref_value_map_factory.h
+++ b/extensions/browser/extension_pref_value_map_factory.h
@@ -26,6 +26,8 @@ class ExtensionPrefValueMapFactory : public BrowserContextKeyedServiceFactory {
 
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
 };
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_PREF_VALUE_MAP_FACTORY_H_
diff --git a/extensions/browser/extension_system.h b/extensions/browser/extension_system.h
index 600ac3a..099a99f 100644
--- a/extensions/browser/extension_system.h
+++ b/extensions/browser/extension_system.h
@@ -30,7 +30,6 @@ class BrowserContext;
 namespace extensions {
 
 class ContentVerifier;
-class EventRouter;
 class Extension;
 class ExtensionSet;
 class InfoMap;
@@ -82,9 +81,6 @@ class ExtensionSystem : public KeyedService {
   // Returns the IO-thread-accessible extension data.
   virtual InfoMap* info_map() = 0;
 
-  // The EventRouter is created at startup.
-  virtual EventRouter* event_router() = 0;
-
   // Returns the QuotaService that limits calls to certain extension functions.
   // Lives on the UI thread. Created at startup.
   virtual QuotaService* quota_service() = 0;
diff --git a/extensions/browser/guest_view/app_view/app_view_guest.cc b/extensions/browser/guest_view/app_view/app_view_guest.cc
index 705274d..9c157d0 100644
--- a/extensions/browser/guest_view/app_view/app_view_guest.cc
+++ b/extensions/browser/guest_view/app_view/app_view_guest.cc
@@ -14,7 +14,6 @@
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_registry.h"
-#include "extensions/browser/extension_system.h"
 #include "extensions/browser/guest_view/app_view/app_view_constants.h"
 #include "extensions/browser/lazy_background_task_queue.h"
 #include "extensions/browser/process_manager.h"
@@ -273,10 +272,10 @@ void AppViewGuest::LaunchAppAndFireEvent(
     scoped_ptr<base::DictionaryValue> data,
     const WebContentsCreatedCallback& callback,
     ExtensionHost* extension_host) {
-  ExtensionSystem* system = ExtensionSystem::Get(browser_context());
-  bool has_event_listener = system->event_router()->ExtensionHasEventListener(
-      extension_host->extension()->id(),
-      app_runtime::OnEmbedRequested::kEventName);
+  bool has_event_listener = EventRouter::Get(browser_context())
+                                ->ExtensionHasEventListener(
+                                    extension_host->extension()->id(),
+                                    app_runtime::OnEmbedRequested::kEventName);
   if (!has_event_listener) {
     callback.Run(nullptr);
     return;
diff --git a/extensions/browser/mock_extension_system.cc b/extensions/browser/mock_extension_system.cc
index 8371c95..845ab9e 100644
--- a/extensions/browser/mock_extension_system.cc
+++ b/extensions/browser/mock_extension_system.cc
@@ -9,7 +9,7 @@
 namespace extensions {
 
 MockExtensionSystem::MockExtensionSystem(content::BrowserContext* context)
-    : browser_context_(context), event_router_(nullptr) {
+    : browser_context_(context) {
 }
 
 MockExtensionSystem::~MockExtensionSystem() {
@@ -46,10 +46,6 @@ InfoMap* MockExtensionSystem::info_map() {
   return nullptr;
 }
 
-EventRouter* MockExtensionSystem::event_router() {
-  return event_router_;
-}
-
 QuotaService* MockExtensionSystem::quota_service() {
   return nullptr;
 }
diff --git a/extensions/browser/mock_extension_system.h b/extensions/browser/mock_extension_system.h
index c06b7bc..05ca13f4 100644
--- a/extensions/browser/mock_extension_system.h
+++ b/extensions/browser/mock_extension_system.h
@@ -25,8 +25,6 @@ class MockExtensionSystem : public ExtensionSystem {
 
   content::BrowserContext* browser_context() { return browser_context_; }
 
-  void set_event_router(EventRouter* router) { event_router_ = router; }
-
   // ExtensionSystem overrides:
   void InitForRegularProfile(bool extensions_enabled) override;
   ExtensionService* extension_service() override;
@@ -36,7 +34,6 @@ class MockExtensionSystem : public ExtensionSystem {
   StateStore* state_store() override;
   StateStore* rules_store() override;
   InfoMap* info_map() override;
-  EventRouter* event_router() override;
   QuotaService* quota_service() override;
   const OneShotEvent& ready() const override;
   ContentVerifier* content_verifier() override;
@@ -47,9 +44,6 @@ class MockExtensionSystem : public ExtensionSystem {
   content::BrowserContext* browser_context_;
   OneShotEvent ready_;
 
-  // Not owned, defaults to null.
-  EventRouter* event_router_;
-
   DISALLOW_COPY_AND_ASSIGN(MockExtensionSystem);
 };
 
diff --git a/extensions/extensions.gypi b/extensions/extensions.gypi
index d661a26..7457d7b 100644
--- a/extensions/extensions.gypi
+++ b/extensions/extensions.gypi
@@ -565,6 +565,8 @@
       'browser/event_page_tracker.h',
       'browser/event_router.cc',
       'browser/event_router.h',
+      'browser/event_router_factory.cc',
+      'browser/event_router_factory.h',
       'browser/extension_error.cc',
       'browser/extension_error.h',
       'browser/extension_function.cc',
diff --git a/extensions/shell/browser/shell_extension_system.cc b/extensions/shell/browser/shell_extension_system.cc
index e5cabb7..e5f5a52 100644
--- a/extensions/shell/browser/shell_extension_system.cc
+++ b/extensions/shell/browser/shell_extension_system.cc
@@ -14,7 +14,6 @@
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "extensions/browser/api/app_runtime/app_runtime_api.h"
-#include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/info_map.h"
@@ -97,8 +96,6 @@ void ShellExtensionSystem::Shutdown() {
 void ShellExtensionSystem::InitForRegularProfile(bool extensions_enabled) {
   runtime_data_.reset(
       new RuntimeData(ExtensionRegistry::Get(browser_context_)));
-  event_router_.reset(
-      new EventRouter(browser_context_, ExtensionPrefs::Get(browser_context_)));
   quota_service_.reset(new QuotaService);
 }
 
@@ -132,10 +129,6 @@ InfoMap* ShellExtensionSystem::info_map() {
   return info_map_.get();
 }
 
-EventRouter* ShellExtensionSystem::event_router() {
-  return event_router_.get();
-}
-
 QuotaService* ShellExtensionSystem::quota_service() {
   return quota_service_.get();
 }
diff --git a/extensions/shell/browser/shell_extension_system.h b/extensions/shell/browser/shell_extension_system.h
index d4db30c..2cbdd5f 100644
--- a/extensions/shell/browser/shell_extension_system.h
+++ b/extensions/shell/browser/shell_extension_system.h
@@ -23,8 +23,6 @@ class BrowserContext;
 
 namespace extensions {
 
-class DeclarativeUserScriptManager;
-class EventRouter;
 class InfoMap;
 class ProcessManager;
 class RendererStartupHelper;
@@ -59,7 +57,6 @@ class ShellExtensionSystem : public ExtensionSystem {
   StateStore* state_store() override;
   StateStore* rules_store() override;
   InfoMap* info_map() override;
-  EventRouter* event_router() override;
   QuotaService* quota_service() override;
   void RegisterExtensionWithRequestContexts(
       const Extension* extension) override;
@@ -78,7 +75,6 @@ class ShellExtensionSystem : public ExtensionSystem {
   scoped_refptr<InfoMap> info_map_;
 
   scoped_ptr<RuntimeData> runtime_data_;
-  scoped_ptr<EventRouter> event_router_;
   scoped_ptr<QuotaService> quota_service_;
 
   // Signaled when the extension system has completed its startup tasks.