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}

23 files changed, 111 insertions, 189 deletions

diff --git a/chrome/browser/extensions/activity_log/activity_log.cc b/chrome/browser/extensions/activity_log/activity_log.cc
index b03a171..9963a25 100644
--- a/chrome/browser/extensions/activity_log/activity_log.cc
+++ b/chrome/browser/extensions/activity_log/activity_log.cc
@@ -382,9 +382,7 @@ ActivityLog::ActivityLog(content::BrowserContext* context)
                            switches::kEnableExtensionActivityLogging) ||
                        watchdog_apps_active_);
 
-  ExtensionSystem::Get(profile_)->ready().Post(
-      FROM_HERE,
-      base::Bind(&ActivityLog::StartObserving, base::Unretained(this)));
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
 
   if (!profile_->IsOffTheRecord())
     uma_policy_ = new UmaPolicy(profile_);
@@ -433,10 +431,6 @@ ActivityLog::~ActivityLog() {
 
 // MAINTAIN STATUS. ------------------------------------------------------------
 
-void ActivityLog::StartObserving() {
-  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
-}
-
 void ActivityLog::ChooseDatabasePolicy() {
   if (!(IsDatabaseEnabled() || IsWatchdogAppActive()))
     return;
diff --git a/chrome/browser/extensions/activity_log/activity_log.h b/chrome/browser/extensions/activity_log/activity_log.h
index e7f4025..8c63b01 100644
--- a/chrome/browser/extensions/activity_log/activity_log.h
+++ b/chrome/browser/extensions/activity_log/activity_log.h
@@ -139,10 +139,6 @@ class ActivityLog : public BrowserContextKeyedAPI,
   // --enable-extension-activity-logging flag is set.
   bool IsDatabaseEnabled();
 
-  // Delayed initialization of ExtensionRegistry which waits until after the
-  // ExtensionSystem/ExtensionService are done with their own setup.
-  void StartObserving();
-
   // ScriptExecutionObserver implementation.
   // Fires when a ContentScript is executed.
   void OnScriptsExecuted(const content::WebContents* web_contents,
diff --git a/chrome/browser/extensions/api/audio_modem/audio_modem_api_unittest.cc b/chrome/browser/extensions/api/audio_modem/audio_modem_api_unittest.cc
index f1fa5ac..3728e67 100644
--- a/chrome/browser/extensions/api/audio_modem/audio_modem_api_unittest.cc
+++ b/chrome/browser/extensions/api/audio_modem/audio_modem_api_unittest.cc
@@ -19,6 +19,7 @@
 #include "components/audio_modem/test/stub_whispernet_client.h"
 #include "extensions/browser/api_test_utils.h"
 #include "extensions/browser/event_router.h"
+#include "extensions/browser/event_router_factory.h"
 
 using audio_modem::AUDIBLE;
 using audio_modem::AudioToken;
@@ -109,15 +110,18 @@ class StubEventRouter : public EventRouter {
   using EventCallback = base::Callback<void(const std::string&,
                                             scoped_ptr<Event>)>;
 
-  StubEventRouter(BrowserContext* context, EventCallback event_callback)
-      : EventRouter(context, nullptr),
-        event_callback_(event_callback) {}
+  explicit StubEventRouter(BrowserContext* context)
+      : EventRouter(context, nullptr) {}
 
   void DispatchEventToExtension(const std::string& extension_id,
                                 scoped_ptr<Event> event) override {
     event_callback_.Run(extension_id, event.Pass());
   }
 
+  void SetEventCallBack(EventCallback event_callback) {
+    event_callback_ = event_callback;
+  }
+
   void ClearEventCallback() {
     event_callback_.Reset();
   }
@@ -126,6 +130,11 @@ class StubEventRouter : public EventRouter {
   EventCallback event_callback_;
 };
 
+// StubEventRouter factory function
+KeyedService* StubEventRouterFactoryFunction(content::BrowserContext* context) {
+  return new StubEventRouter(context);
+}
+
 }  // namespace
 
 class AudioModemApiUnittest : public ExtensionApiUnittest {
@@ -192,14 +201,11 @@ class AudioModemApiUnittest : public ExtensionApiUnittest {
     AudioModemAPI::GetFactoryInstance()->SetTestingFactory(
         profile(), &ApiFactoryFunction);
 
-    scoped_ptr<EventRouter> router(new StubEventRouter(
-        profile(),
-        // The EventRouter is deleted in TearDown().
-        // It will lose this callback before we are destructed.
-        base::Bind(&AudioModemApiUnittest::CaptureEvent,
-                   base::Unretained(this))));
-    static_cast<TestExtensionSystem*>(ExtensionSystem::Get(profile()))
-        ->SetEventRouter(router.Pass());
+    StubEventRouter* stub_event_router = static_cast<StubEventRouter*>(
+        extensions::EventRouterFactory::GetInstance()->SetTestingFactoryAndUse(
+            profile(), &StubEventRouterFactoryFunction));
+    stub_event_router->SetEventCallBack(base::Bind(
+        &AudioModemApiUnittest::CaptureEvent, base::Unretained(this)));
   }
 
   void CaptureEvent(const std::string& extension_id,
diff --git a/chrome/browser/extensions/api/declarative/rules_registry_with_cache_unittest.cc b/chrome/browser/extensions/api/declarative/rules_registry_with_cache_unittest.cc
index e0cb6cc..f5d01e9 100644
--- a/chrome/browser/extensions/api/declarative/rules_registry_with_cache_unittest.cc
+++ b/chrome/browser/extensions/api/declarative/rules_registry_with_cache_unittest.cc
@@ -49,10 +49,8 @@ class RulesRegistryWithCacheTest : public testing::Test {
                                         kRulesRegistryID)) {}
 
   void SetUp() override {
-    env_.GetExtensionPrefs();  // Force creation before adding extensions.
     // Note that env_.MakeExtension below also forces the creation of
     // ExtensionService.
-
     base::DictionaryValue manifest_extra;
     std::string key;
     CHECK(Extension::ProducePEM("test extension 1", &key));
diff --git a/chrome/browser/extensions/api/developer_private/developer_private_api_unittest.cc b/chrome/browser/extensions/api/developer_private/developer_private_api_unittest.cc
index f7e239e..97ac5c2 100644
--- a/chrome/browser/extensions/api/developer_private/developer_private_api_unittest.cc
+++ b/chrome/browser/extensions/api/developer_private/developer_private_api_unittest.cc
@@ -20,6 +20,7 @@
 #include "chrome/test/base/test_browser_window.h"
 #include "components/crx_file/id_util.h"
 #include "content/public/test/test_web_contents_factory.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_error_test_util.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
@@ -41,6 +42,10 @@ KeyedService* BuildAPI(content::BrowserContext* context) {
   return new DeveloperPrivateAPI(context);
 }
 
+KeyedService* BuildEventRouter(content::BrowserContext* profile) {
+  return new EventRouter(profile, ExtensionPrefs::Get(profile));
+}
+
 }  // namespace
 
 class DeveloperPrivateApiUnitTest : public ExtensionServiceTestBase {
@@ -221,9 +226,9 @@ void DeveloperPrivateApiUnitTest::SetUp() {
   browser_.reset(new Browser(params));
 
   // Allow the API to be created.
-  static_cast<TestExtensionSystem*>(ExtensionSystem::Get(profile()))->
-      SetEventRouter(make_scoped_ptr(
-          new EventRouter(profile(), ExtensionPrefs::Get(profile()))));
+  EventRouterFactory::GetInstance()->SetTestingFactory(profile(),
+                                                       &BuildEventRouter);
+
   DeveloperPrivateAPI::GetFactoryInstance()->SetTestingFactory(
       profile(), &BuildAPI);
 }
diff --git a/chrome/browser/extensions/api/device_permissions_manager_unittest.cc b/chrome/browser/extensions/api/device_permissions_manager_unittest.cc
index 86c1803..9863443 100644
--- a/chrome/browser/extensions/api/device_permissions_manager_unittest.cc
+++ b/chrome/browser/extensions/api/device_permissions_manager_unittest.cc
@@ -92,7 +92,6 @@ class DevicePermissionsManagerTest : public testing::Test {
   void SetUp() override {
     testing::Test::SetUp();
     env_.reset(new extensions::TestExtensionEnvironment());
-    env_->GetExtensionPrefs();  // Force creation before adding extensions.
     extension_ =
         env_->MakeExtension(*base::test::ParseJson(
                                 "{"
diff --git a/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api_chromeos_unittest.cc b/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api_chromeos_unittest.cc
index 388c331..6a3de13 100644
--- a/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api_chromeos_unittest.cc
+++ b/chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api_chromeos_unittest.cc
@@ -22,6 +22,8 @@
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/fake_easy_unlock_client.h"
 #include "extensions/browser/event_router.h"
+#include "extensions/browser/event_router_factory.h"
+#include "extensions/browser/extension_prefs.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
 
@@ -429,8 +431,10 @@ KeyedService* BuildTestEasyUnlockService(content::BrowserContext* context) {
 // A fake EventRouter that logs event it dispatches for testing.
 class FakeEventRouter : public extensions::EventRouter {
  public:
-  FakeEventRouter(Profile* profile, extensions::ExtensionPrefs* extension_prefs)
-      : EventRouter(profile, extension_prefs),
+  FakeEventRouter(Profile* profile,
+                  scoped_ptr<extensions::TestExtensionPrefs> extension_prefs)
+      : EventRouter(profile, extension_prefs->prefs()),
+        extension_prefs_(extension_prefs.Pass()),
         event_count_(0) {}
 
   void DispatchEventToExtension(const std::string& extension_id,
@@ -445,42 +449,24 @@ class FakeEventRouter : public extensions::EventRouter {
   const std::string& last_event_name() const { return last_event_name_; }
 
  private:
+  scoped_ptr<extensions::TestExtensionPrefs> extension_prefs_;
   int event_count_;
   std::string last_extension_id_;
   std::string last_event_name_;
 };
 
-// A fake ExtensionSystem that returns a FakeEventRouter for event_router().
-class FakeExtensionSystem : public extensions::TestExtensionSystem {
- public:
-  explicit FakeExtensionSystem(Profile* profile)
-      : TestExtensionSystem(profile),
-        prefs_(new extensions::TestExtensionPrefs(
-            base::ThreadTaskRunnerHandle::Get())) {
-    fake_event_router_.reset(new FakeEventRouter(profile, prefs_->prefs()));
-  }
-
-  extensions::EventRouter* event_router() override {
-    return fake_event_router_.get();
-  }
-
- private:
-  scoped_ptr<extensions::TestExtensionPrefs> prefs_;
-  scoped_ptr<FakeEventRouter> fake_event_router_;
-};
-
-// Factory function to register for the ExtensionSystem.
-KeyedService* BuildFakeExtensionSystem(content::BrowserContext* profile) {
-  return new FakeExtensionSystem(static_cast<Profile*>(profile));
+// FakeEventRouter factory function
+KeyedService* FakeEventRouterFactoryFunction(content::BrowserContext* profile) {
+  scoped_ptr<extensions::TestExtensionPrefs> extension_prefs(
+      new extensions::TestExtensionPrefs(base::ThreadTaskRunnerHandle::Get()));
+  return new FakeEventRouter(static_cast<Profile*>(profile),
+                             extension_prefs.Pass());
 }
 
 TEST_F(EasyUnlockPrivateApiTest, AutoPairing) {
-  FakeExtensionSystem* fake_extension_system =
-      static_cast<FakeExtensionSystem*>(
-          extensions::ExtensionSystemFactory::GetInstance()
-              ->SetTestingFactoryAndUse(profile(), &BuildFakeExtensionSystem));
-  FakeEventRouter* event_router =
-      static_cast<FakeEventRouter*>(fake_extension_system->event_router());
+  FakeEventRouter* event_router = static_cast<FakeEventRouter*>(
+      extensions::EventRouterFactory::GetInstance()->SetTestingFactoryAndUse(
+          profile(), &FakeEventRouterFactoryFunction));
 
   EasyUnlockServiceFactory::GetInstance()->SetTestingFactoryAndUse(
       profile(), &BuildTestEasyUnlockService);
diff --git a/chrome/browser/extensions/api/identity/web_auth_flow.cc b/chrome/browser/extensions/api/identity/web_auth_flow.cc
index ac4d1aa..8af05bb 100644
--- a/chrome/browser/extensions/api/identity/web_auth_flow.cc
+++ b/chrome/browser/extensions/api/identity/web_auth_flow.cc
@@ -101,7 +101,7 @@ void WebAuthFlow::Start() {
         base::FilePath(FILE_PATH_LITERAL("identity_scope_approval_dialog")));
   }
 
-  system->event_router()->DispatchEventWithLazyListener(
+  EventRouter::Get(profile_)->DispatchEventWithLazyListener(
       extension_misc::kIdentityApiUiAppId, event.Pass());
 }
 
diff --git a/chrome/browser/extensions/api/image_writer_private/operation_manager_unittest.cc b/chrome/browser/extensions/api/image_writer_private/operation_manager_unittest.cc
index 1dbe937..bec81903 100644
--- a/chrome/browser/extensions/api/image_writer_private/operation_manager_unittest.cc
+++ b/chrome/browser/extensions/api/image_writer_private/operation_manager_unittest.cc
@@ -11,6 +11,7 @@
 #include "chrome/browser/extensions/test_extension_system.h"
 #include "chrome/test/base/testing_profile.h"
 #include "extensions/browser/event_router.h"
+#include "extensions/browser/event_router_factory.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/login/users/scoped_test_user_manager.h"
@@ -33,23 +34,9 @@ class FakeEventRouter : public extensions::EventRouter {
   }
 };
 
-// A fake ExtensionSystem that returns a FakeEventRouter for event_router().
-class FakeExtensionSystem : public extensions::TestExtensionSystem {
- public:
-  explicit FakeExtensionSystem(Profile* profile)
-      : TestExtensionSystem(profile) {
-    fake_event_router_.reset(new FakeEventRouter(profile));
-  }
-
-  EventRouter* event_router() override { return fake_event_router_.get(); }
-
- private:
-  scoped_ptr<FakeEventRouter> fake_event_router_;
-};
-
-// Factory function to register for the ExtensionSystem.
-KeyedService* BuildFakeExtensionSystem(content::BrowserContext* profile) {
-  return new FakeExtensionSystem(static_cast<Profile*>(profile));
+// FakeEventRouter factory function
+KeyedService* FakeEventRouterFactoryFunction(content::BrowserContext* context) {
+  return new FakeEventRouter(static_cast<Profile*>(context));
 }
 
 namespace {
@@ -76,11 +63,9 @@ class ImageWriterOperationManagerTest : public ImageWriterUnitTestBase {
 
   void SetUp() override {
     ImageWriterUnitTestBase::SetUp();
-    extension_system_ = static_cast<FakeExtensionSystem*>(
-        ExtensionSystemFactory::GetInstance()->
-            SetTestingFactoryAndUse(&test_profile_, &BuildFakeExtensionSystem));
     event_router_ = static_cast<FakeEventRouter*>(
-        extension_system_->event_router());
+        extensions::EventRouterFactory::GetInstance()->SetTestingFactoryAndUse(
+            &test_profile_, &FakeEventRouterFactoryFunction));
   }
 
   bool started_;
@@ -92,7 +77,6 @@ class ImageWriterOperationManagerTest : public ImageWriterUnitTestBase {
   std::string cancel_error_;
 
   TestingProfile test_profile_;
-  FakeExtensionSystem* extension_system_;
   FakeEventRouter* event_router_;
 
 #if defined(OS_CHROMEOS)
diff --git a/chrome/browser/extensions/api/management/management_api_unittest.cc b/chrome/browser/extensions/api/management/management_api_unittest.cc
index 771bd42..a4845ba 100644
--- a/chrome/browser/extensions/api/management/management_api_unittest.cc
+++ b/chrome/browser/extensions/api/management/management_api_unittest.cc
@@ -11,6 +11,7 @@
 #include "chrome/test/base/test_browser_window.h"
 #include "extensions/browser/api/management/management_api.h"
 #include "extensions/browser/api/management/management_api_constants.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
@@ -29,6 +30,10 @@ KeyedService* BuildManagementApi(content::BrowserContext* context) {
   return new ManagementAPI(context);
 }
 
+KeyedService* BuildEventRouter(content::BrowserContext* profile) {
+  return new extensions::EventRouter(profile, ExtensionPrefs::Get(profile));
+}
+
 }  // namespace
 
 namespace constants = extension_management_api_constants;
@@ -74,9 +79,9 @@ void ManagementApiUnitTest::SetUp() {
   InitializeEmptyExtensionService();
   ManagementAPI::GetFactoryInstance()->SetTestingFactory(profile(),
                                                          &BuildManagementApi);
-  static_cast<TestExtensionSystem*>(ExtensionSystem::Get(profile()))->
-      SetEventRouter(make_scoped_ptr(
-          new EventRouter(profile(), ExtensionPrefs::Get(profile()))));
+
+  EventRouterFactory::GetInstance()->SetTestingFactory(profile(),
+                                                       &BuildEventRouter);
 
   browser_window_.reset(new TestBrowserWindow());
   Browser::CreateParams params(profile(), chrome::HOST_DESKTOP_TYPE_NATIVE);
diff --git a/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc b/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
index 86c0c86..84e1f08 100644
--- a/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
+++ b/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
@@ -9,6 +9,7 @@
 #include "chrome/common/extensions/api/mdns.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/test/mock_render_process_host.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/common/manifest_constants.h"
@@ -23,6 +24,12 @@ KeyedService* MDnsAPITestingFactoryFunction(content::BrowserContext* context) {
   return new MDnsAPI(context);
 }
 
+KeyedService* BuildEventRouter(content::BrowserContext* profile) {
+  return new extensions::EventRouter(
+      profile,
+      ExtensionPrefsFactory::GetInstance()->GetForBrowserContext((profile)));
+}
+
 // For ExtensionService interface when it requires a path that is not used.
 base::FilePath bogus_file_pathname(const std::string& name) {
   return base::FilePath(FILE_PATH_LITERAL("//foobar_nonexistent"))
@@ -62,15 +69,12 @@ class MDnsAPITest : public extensions::ExtensionServiceTestBase {
         browser_context(),
         MDnsAPITestingFactoryFunction);
 
-    // Create an event router and associate it with the context.
-    extensions::EventRouter* event_router = CreateEventRouter_();
-    static_cast<TestExtensionSystem*>(
-        ExtensionSystem::Get(browser_context()))->SetEventRouter(
-            scoped_ptr<extensions::EventRouter>(event_router));
+    EventRouterFactory::GetInstance()->SetTestingFactory(browser_context(),
+                                                         &BuildEventRouter);
 
     // Do some sanity checking
-    ASSERT_EQ(event_router, EventRouter::Get(browser_context()));
     ASSERT_TRUE(MDnsAPI::Get(browser_context())); // constructs MDnsAPI
+    ASSERT_TRUE(EventRouter::Get(browser_context()));  // constructs EventRouter
 
     registry_ = new MockDnsSdRegistry(MDnsAPI::Get(browser_context()));
     EXPECT_CALL(*dns_sd_registry(),
@@ -130,14 +134,6 @@ class MDnsAPITest : public extensions::ExtensionServiceTestBase {
     return render_process_host_.get();
   }
 
- protected:
-  virtual extensions::EventRouter* CreateEventRouter_() {
-    return new extensions::EventRouter(
-        browser_context(),
-        ExtensionPrefsFactory::GetInstance()->GetForBrowserContext(
-            browser_context()));
-  }
-
  private:
   // The registry is owned by MDnsAPI, but MDnsAPI does not have an accessor
   // for it, so use a private member.
@@ -230,18 +226,17 @@ class MockEventRouter : public EventRouter {
   MOCK_METHOD1(BroadcastEventPtr, void(Event* event));
 };
 
+KeyedService* MockEventRouterFactoryFunction(content::BrowserContext* profile) {
+  return new MockEventRouter(
+      profile,
+      ExtensionPrefsFactory::GetInstance()->GetForBrowserContext((profile)));
+}
+
 class MDnsAPIMaxServicesTest : public MDnsAPITest {
  public:
   MockEventRouter* event_router() {
     return static_cast<MockEventRouter*>(EventRouter::Get(browser_context()));
   }
- protected:
-  extensions::EventRouter* CreateEventRouter_() override {
-    return new MockEventRouter(
-        browser_context(),
-        ExtensionPrefsFactory::GetInstance()->GetForBrowserContext(
-            browser_context()));
-  }
 };
 
 class EventServiceListSizeMatcher :
@@ -296,6 +291,9 @@ inline testing::Matcher<const Event&> EventServiceListSize(
 }
 
 TEST_F(MDnsAPIMaxServicesTest, OnServiceListDoesNotExceedLimit) {
+  EventRouterFactory::GetInstance()->SetTestingFactory(
+      browser_context(), &MockEventRouterFactoryFunction);
+
    // This check should change when the [value=64] changes in the IDL file.
   EXPECT_EQ(64, api::mdns::MAX_SERVICE_INSTANCES_PER_EVENT);
 
diff --git a/chrome/browser/extensions/api/storage/settings_sync_unittest.cc b/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
index be3de09..100303e 100644
--- a/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
+++ b/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
@@ -19,6 +19,8 @@
 #include "extensions/browser/api/storage/settings_storage_factory.h"
 #include "extensions/browser/api/storage/settings_test_util.h"
 #include "extensions/browser/api/storage/storage_frontend.h"
+#include "extensions/browser/event_router.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/mock_extension_system.h"
 #include "extensions/browser/value_store/testing_value_store.h"
@@ -193,6 +195,15 @@ class TestingValueStoreFactory : public SettingsStorageFactory {
   std::map<std::string, TestingValueStore*> created_;
 };
 
+KeyedService* MockExtensionSystemFactoryFunction(
+    content::BrowserContext* context) {
+  return new MockExtensionSystem(context);
+}
+
+KeyedService* BuildEventRouter(content::BrowserContext* profile) {
+  return new extensions::EventRouter(profile, nullptr);
+}
+
 }  // namespace
 
 class ExtensionSettingsSyncTest : public testing::Test {
@@ -214,8 +225,11 @@ class ExtensionSettingsSyncTest : public testing::Test {
 
     ExtensionsBrowserClient::Get()
         ->GetExtensionSystemFactory()
-        ->SetTestingFactoryAndUse(
-            profile_.get(), &util::MockExtensionSystemWithEventRouter::Build);
+        ->SetTestingFactoryAndUse(profile_.get(),
+                                  &MockExtensionSystemFactoryFunction);
+
+    EventRouterFactory::GetInstance()->SetTestingFactory(profile_.get(),
+                                                         &BuildEventRouter);
   }
 
   void TearDown() override {
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 160ac64..a59eeb9 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -2410,8 +2410,8 @@ bool ExtensionService::ShouldDelayExtensionUpdate(
   if (extensions::BackgroundInfo::HasPersistentBackgroundPage(old)) {
     // Delay installation if the extension listens for the onUpdateAvailable
     // event.
-    return system_->event_router()->ExtensionHasEventListener(
-        extension_id, kOnUpdateAvailableEvent);
+    return extensions::EventRouter::Get(profile_)
+        ->ExtensionHasEventListener(extension_id, kOnUpdateAvailableEvent);
   } else {
     // Delay installation if the extension is not idle.
     return !extensions::util::IsExtensionIdle(extension_id, profile_);
diff --git a/chrome/browser/extensions/extension_service_test_base.cc b/chrome/browser/extensions/extension_service_test_base.cc
index e2b455f..f89098e 100644
--- a/chrome/browser/extensions/extension_service_test_base.cc
+++ b/chrome/browser/extensions/extension_service_test_base.cc
@@ -210,11 +210,8 @@ void ExtensionServiceTestBase::CreateExtensionService(
     const ExtensionServiceInitParams& params) {
   TestExtensionSystem* system =
       static_cast<TestExtensionSystem*>(ExtensionSystem::Get(profile_.get()));
-  if (!params.is_first_run) {
-    ExtensionPrefs* prefs = system->CreateExtensionPrefs(
-        base::CommandLine::ForCurrentProcess(), params.extensions_install_dir);
-    prefs->SetAlertSystemFirstRun();
-  }
+  if (!params.is_first_run)
+    ExtensionPrefs::Get(profile_.get())->SetAlertSystemFirstRun();
 
   service_ =
       system->CreateExtensionService(base::CommandLine::ForCurrentProcess(),
diff --git a/chrome/browser/extensions/extension_system_factory.cc b/chrome/browser/extensions/extension_system_factory.cc
index 3014401..bea8cfb 100644
--- a/chrome/browser/extensions/extension_system_factory.cc
+++ b/chrome/browser/extensions/extension_system_factory.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/ui/global_error/global_error_service_factory.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/declarative_user_script_manager_factory.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/extension_system.h"
@@ -52,6 +53,7 @@ ExtensionSystemSharedFactory::ExtensionSystemSharedFactory()
   DependsOn(RendererStartupHelperFactory::GetInstance());
   DependsOn(BlacklistFactory::GetInstance());
   DependsOn(DeclarativeUserScriptManagerFactory::GetInstance());
+  DependsOn(EventRouterFactory::GetInstance());
   // This depends on ExtensionDownloader which depends on
   // ProfileIdentityProvider which depends on SigninManager.
   DependsOn(SigninManagerFactory::GetInstance());
diff --git a/chrome/browser/extensions/extension_system_impl.cc b/chrome/browser/extensions/extension_system_impl.cc
index d59553d..31a79a8 100644
--- a/chrome/browser/extensions/extension_system_impl.cc
+++ b/chrome/browser/extensions/extension_system_impl.cc
@@ -39,14 +39,12 @@
 #include "content/public/browser/url_data_source.h"
 #include "extensions/browser/content_verifier.h"
 #include "extensions/browser/content_verifier_delegate.h"
-#include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_pref_store.h"
 #include "extensions/browser/extension_pref_value_map.h"
 #include "extensions/browser/extension_pref_value_map_factory.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/info_map.h"
-#include "extensions/browser/lazy_background_task_queue.h"
 #include "extensions/browser/management_policy.h"
 #include "extensions/browser/quota_service.h"
 #include "extensions/browser/runtime_data.h"
@@ -99,7 +97,6 @@ ExtensionSystemImpl::Shared::~Shared() {
 }
 
 void ExtensionSystemImpl::Shared::InitPrefs() {
-  event_router_.reset(new EventRouter(profile_, ExtensionPrefs::Get(profile_)));
   // Two state stores. The latter, which contains declarative rules, must be
   // loaded immediately so that the rules are ready before we issue network
   // requests.
@@ -449,10 +446,6 @@ InfoMap* ExtensionSystemImpl::Shared::info_map() {
   return extension_info_map_.get();
 }
 
-EventRouter* ExtensionSystemImpl::Shared::event_router() {
-  return event_router_.get();
-}
-
 QuotaService* ExtensionSystemImpl::Shared::quota_service() {
   return quota_service_.get();
 }
@@ -517,10 +510,6 @@ StateStore* ExtensionSystemImpl::rules_store() {
 
 InfoMap* ExtensionSystemImpl::info_map() { return shared_->info_map(); }
 
-EventRouter* ExtensionSystemImpl::event_router() {
-  return shared_->event_router();
-}
-
 const OneShotEvent& ExtensionSystemImpl::ready() const {
   return shared_->ready();
 }
diff --git a/chrome/browser/extensions/extension_system_impl.h b/chrome/browser/extensions/extension_system_impl.h
index f4b19c4..92e2457 100644
--- a/chrome/browser/extensions/extension_system_impl.h
+++ b/chrome/browser/extensions/extension_system_impl.h
@@ -16,7 +16,6 @@ namespace extensions {
 
 class ContentVerifier;
 class ExtensionSystemSharedFactory;
-class InstallVerifier;
 class NavigationObserver;
 class SharedUserScriptMaster;
 class StateStoreNotificationObserver;
@@ -43,7 +42,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
   StateStore* state_store() override;                              // shared
   StateStore* rules_store() override;                              // shared
   InfoMap* info_map() override;                                    // shared
-  EventRouter* event_router() override;                            // shared
   QuotaService* quota_service() override;  // shared
 
   void RegisterExtensionWithRequestContexts(
@@ -84,7 +82,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
     ManagementPolicy* management_policy();
     SharedUserScriptMaster* shared_user_script_master();
     InfoMap* info_map();
-    EventRouter* event_router();
     QuotaService* quota_service();
     const OneShotEvent& ready() const { return ready_; }
     ContentVerifier* content_verifier();
@@ -98,9 +95,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
     scoped_ptr<StateStoreNotificationObserver>
         state_store_notification_observer_;
     scoped_ptr<StateStore> rules_store_;
-    // LazyBackgroundTaskQueue is a dependency of
-    // MessageService and EventRouter.
-    scoped_ptr<EventRouter> event_router_;
     scoped_ptr<NavigationObserver> navigation_observer_;
     // Shared memory region manager for scripts statically declared in extension
     // manifests. This region is shared between all extensions.
diff --git a/chrome/browser/extensions/menu_manager_unittest.cc b/chrome/browser/extensions/menu_manager_unittest.cc
index f0cf049..8b1ec7d 100644
--- a/chrome/browser/extensions/menu_manager_unittest.cc
+++ b/chrome/browser/extensions/menu_manager_unittest.cc
@@ -24,6 +24,7 @@
 #include "content/public/common/context_menu_params.h"
 #include "content/public/test/test_browser_thread.h"
 #include "extensions/browser/event_router.h"
+#include "extensions/browser/event_router_factory.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/extension.h"
@@ -481,26 +482,9 @@ class MockEventRouter : public EventRouter {
   DISALLOW_COPY_AND_ASSIGN(MockEventRouter);
 };
 
-// A mock ExtensionSystem to serve our MockEventRouter.
-class MockExtensionSystem : public TestExtensionSystem {
- public:
-  explicit MockExtensionSystem(Profile* profile)
-      : TestExtensionSystem(profile) {}
-
-  EventRouter* event_router() override {
-    if (!mock_event_router_)
-      mock_event_router_.reset(new MockEventRouter(profile_));
-    return mock_event_router_.get();
-  }
-
- private:
-  scoped_ptr<MockEventRouter> mock_event_router_;
-
-  DISALLOW_COPY_AND_ASSIGN(MockExtensionSystem);
-};
-
-KeyedService* BuildMockExtensionSystem(content::BrowserContext* profile) {
-  return new MockExtensionSystem(static_cast<Profile*>(profile));
+// MockEventRouter factory function
+KeyedService* MockEventRouterFactoryFunction(content::BrowserContext* profile) {
+  return new MockEventRouter(static_cast<Profile*>(profile));
 }
 
 }  // namespace
@@ -561,12 +545,9 @@ TEST_F(MenuManagerTest, RemoveOneByOne) {
 
 TEST_F(MenuManagerTest, ExecuteCommand) {
   TestingProfile profile;
-
-  MockExtensionSystem* mock_extension_system =
-      static_cast<MockExtensionSystem*>(ExtensionSystemFactory::GetInstance()->
-          SetTestingFactoryAndUse(&profile, &BuildMockExtensionSystem));
-  MockEventRouter* mock_event_router =
-      static_cast<MockEventRouter*>(mock_extension_system->event_router());
+  MockEventRouter* mock_event_router = static_cast<MockEventRouter*>(
+      EventRouterFactory::GetInstance()->SetTestingFactoryAndUse(
+          &profile, &MockEventRouterFactoryFunction));
 
   content::ContextMenuParams params;
   params.media_type = blink::WebContextMenuData::MediaTypeImage;
diff --git a/chrome/browser/extensions/permission_message_combinations_unittest.cc b/chrome/browser/extensions/permission_message_combinations_unittest.cc
index d4024e5..5e46a53 100644
--- a/chrome/browser/extensions/permission_message_combinations_unittest.cc
+++ b/chrome/browser/extensions/permission_message_combinations_unittest.cc
@@ -31,8 +31,6 @@ class PermissionMessageCombinationsUnittest : public testing::Test {
   // Overridden from testing::Test:
   void SetUp() override {
     testing::Test::SetUp();
-    // Force creation of ExtensionPrefs before adding extensions.
-    env_.GetExtensionPrefs();
   }
 
  protected:
diff --git a/chrome/browser/extensions/permission_messages_unittest.cc b/chrome/browser/extensions/permission_messages_unittest.cc
index 1164f3f..0b45bac 100644
--- a/chrome/browser/extensions/permission_messages_unittest.cc
+++ b/chrome/browser/extensions/permission_messages_unittest.cc
@@ -46,8 +46,6 @@ class PermissionMessagesUnittest : public testing::Test {
   // Overridden from testing::Test:
   void SetUp() override {
     testing::Test::SetUp();
-    // Force creation of ExtensionPrefs before adding extensions.
-    env_.GetExtensionPrefs();
   }
 
  protected:
diff --git a/chrome/browser/extensions/test_extension_environment.cc b/chrome/browser/extensions/test_extension_environment.cc
index 6914ab0..5faf752 100644
--- a/chrome/browser/extensions/test_extension_environment.cc
+++ b/chrome/browser/extensions/test_extension_environment.cc
@@ -14,6 +14,7 @@
 #include "chrome/test/base/testing_profile.h"
 #include "content/public/test/test_utils.h"
 #include "content/public/test/web_contents_tester.h"
+#include "extensions/browser/extension_prefs.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_builder.h"
 #include "extensions/common/value_builder.h"
@@ -81,10 +82,8 @@ ExtensionService* TestExtensionEnvironment::GetExtensionService() {
 }
 
 ExtensionPrefs* TestExtensionEnvironment::GetExtensionPrefs() {
-  if (extension_prefs_ == NULL) {
-    extension_prefs_ = GetExtensionSystem()->CreateExtensionPrefs(
-        base::CommandLine::ForCurrentProcess(), base::FilePath());
-  }
+  if (extension_prefs_ == NULL)
+    extension_prefs_ = ExtensionPrefs::Get(profile_.get());
   return extension_prefs_;
 }
 
diff --git a/chrome/browser/extensions/test_extension_system.cc b/chrome/browser/extensions/test_extension_system.cc
index 9b9ea70..14835f1 100644
--- a/chrome/browser/extensions/test_extension_system.cc
+++ b/chrome/browser/extensions/test_extension_system.cc
@@ -9,21 +9,17 @@
 #include "chrome/browser/extensions/blacklist.h"
 #include "chrome/browser/extensions/extension_management.h"
 #include "chrome/browser/extensions/extension_service.h"
-#include "chrome/browser/extensions/install_verifier.h"
 #include "chrome/browser/extensions/shared_module_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "content/public/browser/browser_thread.h"
-#include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_pref_value_map.h"
 #include "extensions/browser/extension_pref_value_map_factory.h"
 #include "extensions/browser/extension_prefs.h"
-#include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/info_map.h"
-#include "extensions/browser/lazy_background_task_queue.h"
 #include "extensions/browser/management_policy.h"
 #include "extensions/browser/quota_service.h"
 #include "extensions/browser/runtime_data.h"
@@ -59,25 +55,17 @@ ExtensionPrefs* TestExtensionSystem::CreateExtensionPrefs(
   // are not reflected in the pref service. One would need to
   // inject a new ExtensionPrefStore(extension_pref_value_map, false).
 
-  ExtensionPrefs* extension_prefs = ExtensionPrefs::Create(
-      profile_->GetPrefs(),
-      install_directory,
+  return ExtensionPrefs::Create(
+      profile_->GetPrefs(), install_directory,
       ExtensionPrefValueMapFactory::GetForBrowserContext(profile_),
       ExtensionsBrowserClient::Get()->CreateAppSorting().Pass(),
-      extensions_disabled,
-      std::vector<ExtensionPrefsObserver*>());
-    ExtensionPrefsFactory::GetInstance()->SetInstanceForTesting(
-        profile_,
-        extension_prefs);
-    return extension_prefs;
+      extensions_disabled, std::vector<ExtensionPrefsObserver*>());
 }
 
 ExtensionService* TestExtensionSystem::CreateExtensionService(
     const base::CommandLine* command_line,
     const base::FilePath& install_directory,
     bool autoupdate_enabled) {
-  if (!ExtensionPrefs::Get(profile_))
-    CreateExtensionPrefs(command_line, install_directory);
   // The ownership of |value_store_| is immediately transferred to state_store_,
   // but we keep a naked pointer to the TestingValueStore.
   scoped_ptr<TestingValueStore> value_store(new TestingValueStore());
@@ -130,12 +118,6 @@ StateStore* TestExtensionSystem::rules_store() {
 
 InfoMap* TestExtensionSystem::info_map() { return info_map_.get(); }
 
-void TestExtensionSystem::SetEventRouter(scoped_ptr<EventRouter> event_router) {
-  event_router_.reset(event_router.release());
-}
-
-EventRouter* TestExtensionSystem::event_router() { return event_router_.get(); }
-
 QuotaService* TestExtensionSystem::quota_service() {
   return quota_service_.get();
 }
diff --git a/chrome/browser/extensions/test_extension_system.h b/chrome/browser/extensions/test_extension_system.h
index 06a5761..7efd930 100644
--- a/chrome/browser/extensions/test_extension_system.h
+++ b/chrome/browser/extensions/test_extension_system.h
@@ -63,8 +63,6 @@ class TestExtensionSystem : public ExtensionSystem {
   StateStore* rules_store() override;
   TestingValueStore* value_store() { return value_store_; }
   InfoMap* info_map() override;
-  void SetEventRouter(scoped_ptr<EventRouter> event_router);
-  EventRouter* event_router() override;
   QuotaService* quota_service() override;
   const OneShotEvent& ready() const override;
   ContentVerifier* content_verifier() override;
@@ -89,7 +87,6 @@ class TestExtensionSystem : public ExtensionSystem {
   scoped_ptr<RuntimeData> runtime_data_;
   scoped_ptr<ExtensionService> extension_service_;
   scoped_refptr<InfoMap> info_map_;
-  scoped_ptr<EventRouter> event_router_;
   scoped_ptr<QuotaService> quota_service_;
   OneShotEvent ready_;
 };