Use ExtensionRegistry in EventRouter and ApiResourceManager

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/strings/string_util.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/extension_registry_observer.h"
 
@@ skipping 12 matching lines @@
     const {
   scoped_ptr<ExtensionSet> installed_extensions(new ExtensionSet);
   installed_extensions->InsertAll(enabled_extensions_);
   installed_extensions->InsertAll(disabled_extensions_);
   installed_extensions->InsertAll(terminated_extensions_);
   installed_extensions->InsertAll(blacklisted_extensions_);
   return installed_extensions.Pass();
 }
 
 void ExtensionRegistry::AddObserver(ExtensionRegistryObserver* observer) {
+  DCHECK(observer);
   observers_.AddObserver(observer);
 }
 
 void ExtensionRegistry::RemoveObserver(ExtensionRegistryObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
 void ExtensionRegistry::TriggerOnLoaded(const Extension* extension) {
   DCHECK(enabled_extensions_.Contains(extension->id()));
   FOR_EACH_OBSERVER(ExtensionRegistryObserver,
@@ skipping 112 matching lines @@
   disabled_extensions_.set_modification_callback(callback);
 }
 
 void ExtensionRegistry::Shutdown() {
   // Release references to all Extension objects in the sets.
   ClearAll();
   FOR_EACH_OBSERVER(ExtensionRegistryObserver, observers_, OnShutdown(this));
 }
 
 }  // namespace extensions