Remove NOTIFICATION_EXTENSION_ENABLED.

extensions/browser/extension_registry.cc

 // Copyright 2013 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/extension_registry.h"
 
+#include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/extension_registry_observer.h"
 
 namespace extensions {
 
 ExtensionRegistry::ExtensionRegistry(content::BrowserContext* browser_context)
-    : browser_context_(browser_context) {}
+    : browser_context_(browser_context) {
+  lazy_event_dispatch_util_ =
+      base::MakeUnique<LazyEventDispatchUtil>(browser_context_, this);
+}
+
 ExtensionRegistry::~ExtensionRegistry() {}
 
 // static
 ExtensionRegistry* ExtensionRegistry::Get(content::BrowserContext* context) {
   return ExtensionRegistryFactory::GetForBrowserContext(context);
 }
 
 std::unique_ptr<ExtensionSet>
 ExtensionRegistry::GenerateInstalledExtensionsSet() const {
   return GenerateInstalledExtensionsSet(EVERYTHING);
@@ skipping 183 matching lines @@
   blacklisted_extensions_.Clear();
   blocked_extensions_.Clear();
   ready_extensions_.Clear();
 }
 
 void ExtensionRegistry::Shutdown() {
   // Release references to all Extension objects in the sets.
   ClearAll();
   for (auto& observer : observers_)
     observer.OnShutdown(this);
+  lazy_event_dispatch_util_.reset();
+}
+
+LazyEventDispatchUtil* ExtensionRegistry::lazy_event_dispatch_util() {
+  return lazy_event_dispatch_util_.get();
 }
 
 }  // namespace extensions