Remove some NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED

from c/b/extension

and some cleanup.

BUG=354046

Review URL: https://codereview.chromium.org/244143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@265336 0039d316-1c4b-4281-b951-d872f2087c98

20 files changed, 343 insertions, 333 deletions

diff --git a/chrome/browser/extensions/active_tab_permission_granter.cc b/chrome/browser/extensions/active_tab_permission_granter.cc
index 51ea1f2..ef87525 100644
--- a/chrome/browser/extensions/active_tab_permission_granter.cc
+++ b/chrome/browser/extensions/active_tab_permission_granter.cc
@@ -4,19 +4,11 @@
 
 #include "chrome/browser/extensions/active_tab_permission_granter.h"
 
-#include "chrome/browser/chrome_notification_types.h"
-#include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/sessions/session_id.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/navigation_entry.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/notification_source.h"
-#include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_registry.h"
-#include "extensions/browser/extension_system.h"
-#include "extensions/common/extension.h"
 #include "extensions/common/extension_messages.h"
 #include "extensions/common/permissions/permission_set.h"
 #include "extensions/common/permissions/permissions_data.h"
@@ -28,10 +20,13 @@ using content::WebContentsObserver;
 namespace extensions {
 
 ActiveTabPermissionGranter::ActiveTabPermissionGranter(
-    content::WebContents* web_contents, int tab_id, Profile* profile)
-    : WebContentsObserver(web_contents), tab_id_(tab_id),
-      scoped_extension_registry_observer_(this) {
-  scoped_extension_registry_observer_.Add(ExtensionRegistry::Get(profile));
+    content::WebContents* web_contents,
+    int tab_id,
+    Profile* profile)
+    : WebContentsObserver(web_contents),
+      tab_id_(tab_id),
+      extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile));
 }
 
 ActiveTabPermissionGranter::~ActiveTabPermissionGranter() {}
diff --git a/chrome/browser/extensions/active_tab_permission_granter.h b/chrome/browser/extensions/active_tab_permission_granter.h
index be02bd08..bf51ed0 100644
--- a/chrome/browser/extensions/active_tab_permission_granter.h
+++ b/chrome/browser/extensions/active_tab_permission_granter.h
@@ -66,8 +66,8 @@ class ActiveTabPermissionGranter
   ExtensionSet granted_extensions_;
 
   // Listen to extension unloaded notifications.
-  ScopedObserver<ExtensionRegistry,
-                 ExtensionRegistryObserver> scoped_extension_registry_observer_;
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ActiveTabPermissionGranter);
 };
diff --git a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
index 6b11c14..61f6da26 100644
--- a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
+++ b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
@@ -72,11 +72,10 @@ const Extension* GetExtensionById(Profile* profile,
 }  // namespace
 
 GalleryWatchStateTracker::GalleryWatchStateTracker(Profile* profile)
-    : profile_(profile),
-      scoped_extension_registry_observer_(this) {
+    : profile_(profile), extension_registry_observer_(this) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(profile_);
-  scoped_extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
   MediaGalleriesPreferences* preferences =
       g_browser_process->media_file_system_registry()->GetPreferences(profile);
   preferences->AddGalleryChangeObserver(this);
diff --git a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.h b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.h
index 53e082b..7443166 100644
--- a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.h
+++ b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.h
@@ -138,8 +138,8 @@ class GalleryWatchStateTracker
   // Current profile.
   Profile* profile_;
 
-  ScopedObserver<ExtensionRegistry,
-                 ExtensionRegistryObserver> scoped_extension_registry_observer_;
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 
   // A map of watched gallery details, per extension.
   WatchedExtensionsMap watched_extensions_map_;
diff --git a/chrome/browser/extensions/extension_action_manager.cc b/chrome/browser/extensions/extension_action_manager.cc
index 98e2466..b4799741 100644
--- a/chrome/browser/extensions/extension_action_manager.cc
+++ b/chrome/browser/extensions/extension_action_manager.cc
@@ -4,23 +4,14 @@
 
 #include "chrome/browser/extensions/extension_action_manager.h"
 
-#include "chrome/browser/chrome_notification_types.h"
-#include "chrome/browser/extensions/api/system_indicator/system_indicator_manager.h"
 #include "chrome/browser/extensions/api/system_indicator/system_indicator_manager_factory.h"
 #include "chrome/browser/extensions/extension_action.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
-#include "chrome/common/extensions/api/extension_action/action_info.h"
-#include "chrome/common/extensions/api/extension_action/page_action_handler.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
-#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/notification_source.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
-#include "extensions/common/extension.h"
-#include "extensions/common/feature_switch.h"
 
 namespace extensions {
 
@@ -65,11 +56,10 @@ ExtensionActionManagerFactory::GetInstance() {
 }  // namespace
 
 ExtensionActionManager::ExtensionActionManager(Profile* profile)
-    : profile_(profile),
-      scoped_extension_registry_observer_(this) {
+    : profile_(profile), extension_registry_observer_(this) {
   CHECK_EQ(profile, profile->GetOriginalProfile())
       << "Don't instantiate this with an incognito profile.";
-  scoped_extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
 }
 
 ExtensionActionManager::~ExtensionActionManager() {
diff --git a/chrome/browser/extensions/extension_action_manager.h b/chrome/browser/extensions/extension_action_manager.h
index 3315bdc..b78e8a2 100644
--- a/chrome/browser/extensions/extension_action_manager.h
+++ b/chrome/browser/extensions/extension_action_manager.h
@@ -8,7 +8,6 @@
 #include <map>
 #include <string>
 
-#include "base/memory/linked_ptr.h"
 #include "base/scoped_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "extensions/browser/extension_registry_observer.h"
@@ -52,8 +51,8 @@ class ExtensionActionManager : public KeyedService,
   Profile* profile_;
 
   // Listen to extension unloaded notifications.
-  ScopedObserver<ExtensionRegistry,
-                 ExtensionRegistryObserver> scoped_extension_registry_observer_;
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 
   // Keyed by Extension ID.  These maps are populated lazily when their
   // ExtensionAction is first requested, and the entries are removed when the
diff --git a/chrome/browser/extensions/extension_gcm_app_handler.cc b/chrome/browser/extensions/extension_gcm_app_handler.cc
index 86ef5bb..879a351 100644
--- a/chrome/browser/extensions/extension_gcm_app_handler.cc
+++ b/chrome/browser/extensions/extension_gcm_app_handler.cc
@@ -44,14 +44,9 @@ ExtensionGCMAppHandler::GetFactoryInstance() {
 
 ExtensionGCMAppHandler::ExtensionGCMAppHandler(content::BrowserContext* context)
     : profile_(Profile::FromBrowserContext(context)),
+      extension_registry_observer_(this),
       weak_factory_(this) {
-  // Listen to various extension related notifications.
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
   registrar_.Add(this,
                  chrome::NOTIFICATION_EXTENSION_UNINSTALLED,
                  content::Source<Profile>(profile_));
@@ -100,38 +95,34 @@ void ExtensionGCMAppHandler::OnSendError(
 #endif
 }
 
+void ExtensionGCMAppHandler::OnExtensionLoaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension) {
+  if (IsGCMPermissionEnabled(extension))
+    GetGCMProfileService()->AddAppHandler(extension->id(), this);
+}
+
+void ExtensionGCMAppHandler::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  if (IsGCMPermissionEnabled(extension))
+    GetGCMProfileService()->RemoveAppHandler(extension->id());
+}
+
 void ExtensionGCMAppHandler::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
-  switch (type) {
-    case chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
-      const Extension* extension = content::Details<Extension>(details).ptr();
-      if (IsGCMPermissionEnabled(extension))
-        GetGCMProfileService()->AddAppHandler(extension->id(), this);
-      break;
-    }
-    case chrome:: NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED: {
-      const Extension* extension =
-          content::Details<UnloadedExtensionInfo>(details)->extension;
-      if (IsGCMPermissionEnabled(extension))
-        GetGCMProfileService()->RemoveAppHandler(extension->id());
-      break;
-    }
-    case chrome:: NOTIFICATION_EXTENSION_UNINSTALLED: {
-      const Extension* extension = content::Details<Extension>(details).ptr();
-      if (IsGCMPermissionEnabled(extension)) {
-        GetGCMProfileService()->Unregister(
-            extension->id(),
-            base::Bind(&ExtensionGCMAppHandler::OnUnregisterCompleted,
-                       weak_factory_.GetWeakPtr(),
-                       extension->id()));
-        GetGCMProfileService()->RemoveAppHandler(extension->id());
-      }
-      break;
-    }
-    default:
-      NOTREACHED();
+  DCHECK_EQ(chrome::NOTIFICATION_EXTENSION_UNINSTALLED, type);
+  const Extension* extension = content::Details<Extension>(details).ptr();
+  if (IsGCMPermissionEnabled(extension)) {
+    GetGCMProfileService()->Unregister(
+        extension->id(),
+        base::Bind(&ExtensionGCMAppHandler::OnUnregisterCompleted,
+                   weak_factory_.GetWeakPtr(),
+                   extension->id()));
+    GetGCMProfileService()->RemoveAppHandler(extension->id());
   }
 }
 
diff --git a/chrome/browser/extensions/extension_gcm_app_handler.h b/chrome/browser/extensions/extension_gcm_app_handler.h
index c1fac2d..8e90ddf 100644
--- a/chrome/browser/extensions/extension_gcm_app_handler.h
+++ b/chrome/browser/extensions/extension_gcm_app_handler.h
@@ -7,10 +7,12 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
 #include "chrome/browser/services/gcm/gcm_app_handler.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
+#include "extensions/browser/extension_registry_observer.h"
 #include "google_apis/gcm/gcm_client.h"
 
 class Profile;
@@ -23,12 +25,14 @@ class GCMProfileService;
 
 namespace extensions {
 
+class ExtensionRegistry;
 class GcmJsEventRouter;
 
 // Defines the interface to provide handling logic for a given app.
 class ExtensionGCMAppHandler : public gcm::GCMAppHandler,
                                public BrowserContextKeyedAPI,
-                               public content::NotificationObserver {
+                               public content::NotificationObserver,
+                               public ExtensionRegistryObserver {
  public:
   explicit ExtensionGCMAppHandler(content::BrowserContext* context);
   virtual ~ExtensionGCMAppHandler();
@@ -59,6 +63,14 @@ class ExtensionGCMAppHandler : public gcm::GCMAppHandler,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   gcm::GCMProfileService* GetGCMProfileService() const;
 
   // BrowserContextKeyedAPI implementation.
@@ -68,6 +80,10 @@ class ExtensionGCMAppHandler : public gcm::GCMAppHandler,
   Profile* profile_;
   content::NotificationRegistrar registrar_;
 
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
 #if !defined(OS_ANDROID)
   scoped_ptr<extensions::GcmJsEventRouter> js_event_router_;
 #endif
diff --git a/chrome/browser/extensions/extension_keybinding_registry.cc b/chrome/browser/extensions/extension_keybinding_registry.cc
index 623f78e..d372e13 100644
--- a/chrome/browser/extensions/extension_keybinding_registry.cc
+++ b/chrome/browser/extensions/extension_keybinding_registry.cc
@@ -12,6 +12,7 @@
 #include "chrome/common/extensions/command.h"
 #include "content/public/browser/browser_context.h"
 #include "extensions/browser/event_router.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/manifest_constants.h"
@@ -22,21 +23,19 @@ ExtensionKeybindingRegistry::ExtensionKeybindingRegistry(
     content::BrowserContext* context,
     ExtensionFilter extension_filter,
     Delegate* delegate)
-    : profile_(Profile::FromBrowserContext(context)),
+    : browser_context_(context),
       extension_filter_(extension_filter),
-      delegate_(delegate) {
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile_->GetOriginalProfile()));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-                 content::Source<Profile>(profile_->GetOriginalProfile()));
+      delegate_(delegate),
+      extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(browser_context_));
+
+  Profile* profile = Profile::FromBrowserContext(browser_context_);
   registrar_.Add(this,
                  chrome::NOTIFICATION_EXTENSION_COMMAND_ADDED,
-                 content::Source<Profile>(profile_->GetOriginalProfile()));
+                 content::Source<Profile>(profile->GetOriginalProfile()));
   registrar_.Add(this,
                  chrome::NOTIFICATION_EXTENSION_COMMAND_REMOVED,
-                 content::Source<Profile>(profile_->GetOriginalProfile()));
+                 content::Source<Profile>(profile->GetOriginalProfile()));
 }
 
 ExtensionKeybindingRegistry::~ExtensionKeybindingRegistry() {
@@ -73,7 +72,7 @@ void ExtensionKeybindingRegistry::RemoveExtensionKeybinding(
 
 void ExtensionKeybindingRegistry::Init() {
   ExtensionService* service =
-      extensions::ExtensionSystem::Get(profile_)->extension_service();
+      ExtensionSystem::Get(browser_context_)->extension_service();
   if (!service)
     return;  // ExtensionService can be null during testing.
 
@@ -98,7 +97,7 @@ bool ExtensionKeybindingRegistry::NotifyEventTargets(
 void ExtensionKeybindingRegistry::CommandExecuted(
     const std::string& extension_id, const std::string& command) {
   ExtensionService* service =
-      ExtensionSystem::Get(profile_)->extension_service();
+      ExtensionSystem::Get(browser_context_)->extension_service();
 
   const Extension* extension = service->extensions()->GetByID(extension_id);
   if (!extension)
@@ -117,9 +116,9 @@ void ExtensionKeybindingRegistry::CommandExecuted(
   args->Append(new base::StringValue(command));
 
   scoped_ptr<Event> event(new Event("commands.onCommand", args.Pass()));
-  event->restrict_to_browser_context = profile_;
+  event->restrict_to_browser_context = browser_context_;
   event->user_gesture = EventRouter::USER_GESTURE_ENABLED;
-  EventRouter::Get(profile_)
+  EventRouter::Get(browser_context_)
       ->DispatchEventToExtension(extension_id, event.Pass());
 }
 
@@ -165,34 +164,36 @@ void ExtensionKeybindingRegistry::ExecuteCommand(
   ExecuteCommands(accelerator, extension_id);
 }
 
+void ExtensionKeybindingRegistry::OnExtensionLoaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension) {
+  if (ExtensionMatchesFilter(extension))
+    AddExtensionKeybinding(extension, std::string());
+}
+
+void ExtensionKeybindingRegistry::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  if (ExtensionMatchesFilter(extension))
+    RemoveExtensionKeybinding(extension, std::string());
+}
+
 void ExtensionKeybindingRegistry::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
-    case chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
-      const extensions::Extension* extension =
-          content::Details<const extensions::Extension>(details).ptr();
-      if (ExtensionMatchesFilter(extension))
-        AddExtensionKeybinding(extension, std::string());
-      break;
-    }
-    case chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED: {
-      const extensions::Extension* extension =
-          content::Details<UnloadedExtensionInfo>(details)->extension;
-      if (ExtensionMatchesFilter(extension))
-        RemoveExtensionKeybinding(extension, std::string());
-      break;
-    }
     case chrome::NOTIFICATION_EXTENSION_COMMAND_ADDED:
     case chrome::NOTIFICATION_EXTENSION_COMMAND_REMOVED: {
       std::pair<const std::string, const std::string>* payload =
           content::Details<std::pair<const std::string, const std::string> >(
               details).ptr();
 
-      const extensions::Extension* extension =
-          ExtensionSystem::Get(profile_)->extension_service()->
-              extensions()->GetByID(payload->first);
+      const Extension* extension = ExtensionSystem::Get(browser_context_)
+                                       ->extension_service()
+                                       ->extensions()
+                                       ->GetByID(payload->first);
       // During install and uninstall the extension won't be found. We'll catch
       // those events above, with the LOADED/UNLOADED, so we ignore this event.
       if (!extension)
diff --git a/chrome/browser/extensions/extension_keybinding_registry.h b/chrome/browser/extensions/extension_keybinding_registry.h
index 5c4cc50..1fb656c 100644
--- a/chrome/browser/extensions/extension_keybinding_registry.h
+++ b/chrome/browser/extensions/extension_keybinding_registry.h
@@ -10,12 +10,12 @@
 #include <string>
 
 #include "base/compiler_specific.h"
+#include "base/scoped_observer.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_source.h"
-
-class Profile;
+#include "extensions/browser/extension_registry_observer.h"
 
 namespace content {
 class BrowserContext;
@@ -29,11 +29,13 @@ namespace extensions {
 
 class ActiveTabPermissionGranter;
 class Extension;
+class ExtensionRegistry;
 
 // The ExtensionKeybindingRegistry is a class that handles the cross-platform
 // logic for keyboard accelerators. See platform-specific implementations for
 // implementation details for each platform.
-class ExtensionKeybindingRegistry : public content::NotificationObserver {
+class ExtensionKeybindingRegistry : public content::NotificationObserver,
+                                    public ExtensionRegistryObserver {
  public:
   enum ExtensionFilter {
     ALL_EXTENSIONS,
@@ -64,11 +66,6 @@ class ExtensionKeybindingRegistry : public content::NotificationObserver {
   void ExecuteCommand(const std::string& extension_id,
                       const ui::Accelerator& accelerator);
 
-  // Overridden from content::NotificationObserver:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
  protected:
   // Add extension keybinding for the events defined by the |extension|.
   // |command_name| is optional, but if not blank then only the command
@@ -125,6 +122,19 @@ class ExtensionKeybindingRegistry : public content::NotificationObserver {
   bool IsEventTargetsEmpty() const;
 
  private:
+  // Overridden from content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   // Returns true if the |extension| matches our extension filter.
   bool ExtensionMatchesFilter(const extensions::Extension* extension);
 
@@ -138,8 +148,7 @@ class ExtensionKeybindingRegistry : public content::NotificationObserver {
   // The content notification registrar for listening to extension events.
   content::NotificationRegistrar registrar_;
 
-  // Weak pointer to our profile. Not owned by us.
-  Profile* profile_;
+  content::BrowserContext* browser_context_;
 
   // What extensions to register keybindings for.
   ExtensionFilter extension_filter_;
@@ -158,6 +167,10 @@ class ExtensionKeybindingRegistry : public content::NotificationObserver {
   typedef std::map<ui::Accelerator, TargetList> EventTargets;
   EventTargets event_targets_;
 
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionKeybindingRegistry);
 };
 
diff --git a/chrome/browser/extensions/extension_warning_service.cc b/chrome/browser/extensions/extension_warning_service.cc
index bfb9977..ab929a2 100644
--- a/chrome/browser/extensions/extension_warning_service.cc
+++ b/chrome/browser/extensions/extension_warning_service.cc
@@ -4,28 +4,23 @@
 
 #include "chrome/browser/extensions/extension_warning_service.h"
 
-#include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/browser/notification_service.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
-#include "extensions/common/extension.h"
 
 using content::BrowserThread;
 
 namespace extensions {
 
 ExtensionWarningService::ExtensionWarningService(Profile* profile)
-    : profile_(profile),
-      scoped_extension_registry_observer_(this) {
+    : profile_(profile), extension_registry_observer_(this) {
   DCHECK(CalledOnValidThread());
   if (profile_) {
-    scoped_extension_registry_observer_.Add(
+    extension_registry_observer_.Add(
         ExtensionRegistry::Get(profile_->GetOriginalProfile()));
   }
 }
diff --git a/chrome/browser/extensions/extension_warning_service.h b/chrome/browser/extensions/extension_warning_service.h
index 5a6ecf7..c311859 100644
--- a/chrome/browser/extensions/extension_warning_service.h
+++ b/chrome/browser/extensions/extension_warning_service.h
@@ -85,8 +85,8 @@ class ExtensionWarningService : public ExtensionRegistryObserver,
   Profile* profile_;
 
   // Listen to extension unloaded notifications.
-  ScopedObserver<ExtensionRegistry,
-                 ExtensionRegistryObserver> scoped_extension_registry_observer_;
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 
   ObserverList<Observer> observer_list_;
 };
diff --git a/chrome/browser/extensions/extension_web_ui_override_registrar.cc b/chrome/browser/extensions/extension_web_ui_override_registrar.cc
index 56c84a6..a0ffd99 100644
--- a/chrome/browser/extensions/extension_web_ui_override_registrar.cc
+++ b/chrome/browser/extensions/extension_web_ui_override_registrar.cc
@@ -5,44 +5,36 @@
 #include "chrome/browser/extensions/extension_web_ui_override_registrar.h"
 
 #include "base/lazy_instance.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_web_ui.h"
 #include "chrome/browser/profiles/profile.h"
-#include "content/public/browser/notification_details.h"
-#include "content/public/browser/notification_service.h"
+#include "extensions/browser/extension_registry.h"
 
 namespace extensions {
 
 ExtensionWebUIOverrideRegistrar::ExtensionWebUIOverrideRegistrar(
     content::BrowserContext* context)
-    : profile_(Profile::FromBrowserContext(context)) {
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
+    : extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(context));
 }
 
 ExtensionWebUIOverrideRegistrar::~ExtensionWebUIOverrideRegistrar() {
 }
 
-void ExtensionWebUIOverrideRegistrar::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  if (type == chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED) {
-    const Extension* extension =
-        content::Details<const Extension>(details).ptr();
-    ExtensionWebUI::RegisterChromeURLOverrides(
-        profile_, URLOverrides::GetChromeURLOverrides(extension));
-
-  } else if (type == chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED) {
-    const Extension* extension =
-        content::Details<UnloadedExtensionInfo>(details)->extension;
-    ExtensionWebUI::UnregisterChromeURLOverrides(
-        profile_, URLOverrides::GetChromeURLOverrides(extension));
-  }
+void ExtensionWebUIOverrideRegistrar::OnExtensionLoaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension) {
+  ExtensionWebUI::RegisterChromeURLOverrides(
+      Profile::FromBrowserContext(browser_context),
+      URLOverrides::GetChromeURLOverrides(extension));
+}
+
+void ExtensionWebUIOverrideRegistrar::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  ExtensionWebUI::UnregisterChromeURLOverrides(
+      Profile::FromBrowserContext(browser_context),
+      URLOverrides::GetChromeURLOverrides(extension));
 }
 
 static base::LazyInstance<
diff --git a/chrome/browser/extensions/extension_web_ui_override_registrar.h b/chrome/browser/extensions/extension_web_ui_override_registrar.h
index 6b02ac19..4c3344e7 100644
--- a/chrome/browser/extensions/extension_web_ui_override_registrar.h
+++ b/chrome/browser/extensions/extension_web_ui_override_registrar.h
@@ -6,20 +6,19 @@
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_WEB_UI_OVERRIDE_REGISTRAR_H_
 
 #include "base/basictypes.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "base/scoped_observer.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
-
-class Profile;
+#include "extensions/browser/extension_registry_observer.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
+class ExtensionRegistry;
 
 class ExtensionWebUIOverrideRegistrar : public BrowserContextKeyedAPI,
-                                        public content::NotificationObserver {
+                                        public ExtensionRegistryObserver {
  public:
   explicit ExtensionWebUIOverrideRegistrar(content::BrowserContext* context);
   virtual ~ExtensionWebUIOverrideRegistrar();
@@ -28,21 +27,25 @@ class ExtensionWebUIOverrideRegistrar : public BrowserContextKeyedAPI,
   static BrowserContextKeyedAPIFactory<ExtensionWebUIOverrideRegistrar>*
       GetFactoryInstance();
 
-  // content::NotificationObserver implementation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
  private:
   friend class BrowserContextKeyedAPIFactory<ExtensionWebUIOverrideRegistrar>;
 
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   // BrowserContextKeyedAPI implementation.
   static const char* service_name() {
     return "ExtensionWebUIOverrideRegistrar";
   }
 
-  Profile* const profile_;
-  content::NotificationRegistrar registrar_;
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionWebUIOverrideRegistrar);
 };
diff --git a/chrome/browser/extensions/install_tracker.cc b/chrome/browser/extensions/install_tracker.cc
index a37e2f5..81e72fed 100644
--- a/chrome/browser/extensions/install_tracker.cc
+++ b/chrome/browser/extensions/install_tracker.cc
@@ -11,26 +11,24 @@
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/notification_service.h"
 #include "extensions/browser/extension_prefs.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/pref_names.h"
 
 namespace extensions {
 
 InstallTracker::InstallTracker(Profile* profile,
-                               extensions::ExtensionPrefs* prefs) {
-  AppSorting* sorting = prefs->app_sorting();
+                               extensions::ExtensionPrefs* prefs)
+    : extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile));
 
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_INSTALLED,
       content::Source<Profile>(profile));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile));
-  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-      content::Source<Profile>(profile));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNINSTALLED,
       content::Source<Profile>(profile));
   registrar_.Add(this,
                  chrome::NOTIFICATION_EXTENSION_UPDATE_DISABLED,
                  content::Source<Profile>(profile));
+  AppSorting* sorting = prefs->app_sorting();
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LAUNCHER_REORDERED,
       content::Source<AppSorting>(sorting));
   registrar_.Add(this, chrome::NOTIFICATION_APP_INSTALLED_TO_APPLIST,
@@ -97,6 +95,19 @@ void InstallTracker::Shutdown() {
   FOR_EACH_OBSERVER(InstallObserver, observers_, OnShutdown());
 }
 
+void InstallTracker::OnExtensionLoaded(content::BrowserContext* browser_context,
+                                       const Extension* extension) {
+  FOR_EACH_OBSERVER(InstallObserver, observers_, OnExtensionLoaded(extension));
+}
+
+void InstallTracker::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  FOR_EACH_OBSERVER(
+      InstallObserver, observers_, OnExtensionUnloaded(extension));
+}
+
 void InstallTracker::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
@@ -109,21 +120,6 @@ void InstallTracker::Observe(int type,
                         OnExtensionInstalled(extension));
       break;
     }
-    case chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
-      const Extension* extension =
-          content::Details<const Extension>(details).ptr();
-      FOR_EACH_OBSERVER(InstallObserver, observers_,
-                        OnExtensionLoaded(extension));
-      break;
-    }
-    case chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED: {
-      const content::Details<extensions::UnloadedExtensionInfo>& unload_info(
-          details);
-      const Extension* extension = unload_info->extension;
-      FOR_EACH_OBSERVER(InstallObserver, observers_,
-                        OnExtensionUnloaded(extension));
-      break;
-    }
     case chrome::NOTIFICATION_EXTENSION_UNINSTALLED: {
       const Extension* extension =
           content::Details<const Extension>(details).ptr();
diff --git a/chrome/browser/extensions/install_tracker.h b/chrome/browser/extensions/install_tracker.h
index ea3c945..8342ec9 100644
--- a/chrome/browser/extensions/install_tracker.h
+++ b/chrome/browser/extensions/install_tracker.h
@@ -7,10 +7,12 @@
 
 #include "base/observer_list.h"
 #include "base/prefs/pref_change_registrar.h"
+#include "base/scoped_observer.h"
 #include "chrome/browser/extensions/install_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry_observer.h"
 
 class Profile;
 
@@ -21,9 +23,11 @@ class BrowserContext;
 namespace extensions {
 
 class ExtensionPrefs;
+class ExtensionRegistry;
 
 class InstallTracker : public KeyedService,
-                       public content::NotificationObserver {
+                       public content::NotificationObserver,
+                       public ExtensionRegistryObserver {
  public:
   InstallTracker(Profile* profile,
                  extensions::ExtensionPrefs* prefs);
@@ -43,21 +47,33 @@ class InstallTracker : public KeyedService,
   void OnFinishCrxInstall(const std::string& extension_id, bool success);
   void OnInstallFailure(const std::string& extension_id);
 
-  // Overriddes for KeyedService:
+  // Overriddes for KeyedService.
   virtual void Shutdown() OVERRIDE;
 
-  // content::NotificationObserver
+ private:
+  void OnAppsReordered();
+
+  // content::NotificationObserver.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
- private:
-  void OnAppsReordered();
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
 
   ObserverList<InstallObserver> observers_;
   content::NotificationRegistrar registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(InstallTracker);
 };
 
diff --git a/chrome/browser/extensions/plugin_manager.cc b/chrome/browser/extensions/plugin_manager.cc
index 57506d1..526aa0c 100644
--- a/chrome/browser/extensions/plugin_manager.cc
+++ b/chrome/browser/extensions/plugin_manager.cc
@@ -6,33 +6,27 @@
 #include "base/lazy_instance.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/plugin_manager.h"
 #include "chrome/browser/plugins/chrome_plugin_service_filter.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/extensions/api/plugins/plugins_handler.h"
-#include "content/public/browser/notification_details.h"
-#include "content/public/browser/notification_source.h"
 #include "content/public/browser/plugin_service.h"
 #include "content/public/common/pepper_plugin_info.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/common/extension.h"
 #include "url/gurl.h"
 
 using content::PluginService;
 
-static const char* kNaClPluginMimeType = "application/x-nacl";
+static const char kNaClPluginMimeType[] = "application/x-nacl";
 
 namespace extensions {
 
 PluginManager::PluginManager(content::BrowserContext* context)
-    : profile_(Profile::FromBrowserContext(context)) {
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
+    : profile_(Profile::FromBrowserContext(context)),
+      extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
 }
 
 PluginManager::~PluginManager() {
@@ -47,85 +41,78 @@ PluginManager::GetFactoryInstance() {
   return g_factory.Pointer();
 }
 
-void PluginManager::Observe(int type,
-                            const content::NotificationSource& source,
-                            const content::NotificationDetails& details) {
-  if (type == chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED) {
-    const Extension* extension =
-        content::Details<const Extension>(details).ptr();
-
-    bool plugins_or_nacl_changed = false;
-    if (PluginInfo::HasPlugins(extension)) {
-      const PluginInfo::PluginVector* plugins =
-          PluginInfo::GetPlugins(extension);
-      CHECK(plugins);
-      plugins_or_nacl_changed = true;
-      for (PluginInfo::PluginVector::const_iterator plugin = plugins->begin();
-           plugin != plugins->end(); ++plugin) {
-        PluginService::GetInstance()->RefreshPlugins();
-        PluginService::GetInstance()->AddExtraPluginPath(plugin->path);
-        ChromePluginServiceFilter* filter =
-            ChromePluginServiceFilter::GetInstance();
-        if (plugin->is_public) {
-          filter->RestrictPluginToProfileAndOrigin(
-              plugin->path, profile_, GURL());
-        } else {
-          filter->RestrictPluginToProfileAndOrigin(
-              plugin->path, profile_, extension->url());
-        }
+void PluginManager::OnExtensionLoaded(content::BrowserContext* browser_context,
+                                      const Extension* extension) {
+  bool plugins_or_nacl_changed = false;
+  if (PluginInfo::HasPlugins(extension)) {
+    const PluginInfo::PluginVector* plugins = PluginInfo::GetPlugins(extension);
+    CHECK(plugins);
+    plugins_or_nacl_changed = true;
+    for (PluginInfo::PluginVector::const_iterator plugin = plugins->begin();
+         plugin != plugins->end();
+         ++plugin) {
+      PluginService::GetInstance()->RefreshPlugins();
+      PluginService::GetInstance()->AddExtraPluginPath(plugin->path);
+      ChromePluginServiceFilter* filter =
+          ChromePluginServiceFilter::GetInstance();
+      if (plugin->is_public) {
+        filter->RestrictPluginToProfileAndOrigin(
+            plugin->path, profile_, GURL());
+      } else {
+        filter->RestrictPluginToProfileAndOrigin(
+            plugin->path, profile_, extension->url());
       }
     }
+  }
 
-    const NaClModuleInfo::List* nacl_modules =
-        NaClModuleInfo::GetNaClModules(extension);
-    if (nacl_modules) {
-      plugins_or_nacl_changed = true;
-      for (NaClModuleInfo::List::const_iterator module = nacl_modules->begin();
-           module != nacl_modules->end(); ++module) {
-        RegisterNaClModule(*module);
-      }
-      UpdatePluginListWithNaClModules();
+  const NaClModuleInfo::List* nacl_modules =
+      NaClModuleInfo::GetNaClModules(extension);
+  if (nacl_modules) {
+    plugins_or_nacl_changed = true;
+    for (NaClModuleInfo::List::const_iterator module = nacl_modules->begin();
+         module != nacl_modules->end();
+         ++module) {
+      RegisterNaClModule(*module);
     }
+    UpdatePluginListWithNaClModules();
+  }
 
-    if (plugins_or_nacl_changed)
-      PluginService::GetInstance()->PurgePluginListCache(profile_, false);
-
-  } else if (type == chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED) {
-    const Extension* extension =
-        content::Details<UnloadedExtensionInfo>(details)->extension;
-
-    bool plugins_or_nacl_changed = false;
-    if (PluginInfo::HasPlugins(extension)) {
-      const PluginInfo::PluginVector* plugins =
-          PluginInfo::GetPlugins(extension);
-      plugins_or_nacl_changed = true;
-      for (PluginInfo::PluginVector::const_iterator plugin = plugins->begin();
-           plugin != plugins->end(); ++plugin) {
-        PluginService::GetInstance()->ForcePluginShutdown(plugin->path);
-        PluginService::GetInstance()->RefreshPlugins();
-        PluginService::GetInstance()->RemoveExtraPluginPath(plugin->path);
-        ChromePluginServiceFilter::GetInstance()->UnrestrictPlugin(
-            plugin->path);
-      }
-    }
+  if (plugins_or_nacl_changed)
+    PluginService::GetInstance()->PurgePluginListCache(profile_, false);
+}
 
-    const NaClModuleInfo::List* nacl_modules =
-        NaClModuleInfo::GetNaClModules(extension);
-    if (nacl_modules) {
-      plugins_or_nacl_changed = true;
-      for (NaClModuleInfo::List::const_iterator module = nacl_modules->begin();
-           module != nacl_modules->end(); ++module) {
-        UnregisterNaClModule(*module);
-      }
-      UpdatePluginListWithNaClModules();
+void PluginManager::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  bool plugins_or_nacl_changed = false;
+  if (PluginInfo::HasPlugins(extension)) {
+    const PluginInfo::PluginVector* plugins = PluginInfo::GetPlugins(extension);
+    plugins_or_nacl_changed = true;
+    for (PluginInfo::PluginVector::const_iterator plugin = plugins->begin();
+         plugin != plugins->end();
+         ++plugin) {
+      PluginService::GetInstance()->ForcePluginShutdown(plugin->path);
+      PluginService::GetInstance()->RefreshPlugins();
+      PluginService::GetInstance()->RemoveExtraPluginPath(plugin->path);
+      ChromePluginServiceFilter::GetInstance()->UnrestrictPlugin(plugin->path);
     }
+  }
 
-    if (plugins_or_nacl_changed)
-      PluginService::GetInstance()->PurgePluginListCache(profile_, false);
-
-  } else {
-    NOTREACHED();
+  const NaClModuleInfo::List* nacl_modules =
+      NaClModuleInfo::GetNaClModules(extension);
+  if (nacl_modules) {
+    plugins_or_nacl_changed = true;
+    for (NaClModuleInfo::List::const_iterator module = nacl_modules->begin();
+         module != nacl_modules->end();
+         ++module) {
+      UnregisterNaClModule(*module);
+    }
+    UpdatePluginListWithNaClModules();
   }
+
+  if (plugins_or_nacl_changed)
+    PluginService::GetInstance()->PurgePluginListCache(profile_, false);
 }
 
 void PluginManager::RegisterNaClModule(const NaClModuleInfo& info) {
diff --git a/chrome/browser/extensions/plugin_manager.h b/chrome/browser/extensions/plugin_manager.h
index c66ac5a..9c8d046 100644
--- a/chrome/browser/extensions/plugin_manager.h
+++ b/chrome/browser/extensions/plugin_manager.h
@@ -5,10 +5,10 @@
 #ifndef CHROME_BROWSER_EXTENSIONS_PLUGIN_MANAGER_H_
 #define CHROME_BROWSER_EXTENSIONS_PLUGIN_MANAGER_H_
 
+#include "base/scoped_observer.h"
 #include "chrome/common/extensions/manifest_handlers/nacl_modules_handler.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
+#include "extensions/browser/extension_registry_observer.h"
 
 class GURL;
 class Profile;
@@ -18,9 +18,10 @@ class BrowserContext;
 }
 
 namespace extensions {
+class ExtensionRegistry;
 
 class PluginManager : public BrowserContextKeyedAPI,
-                      public content::NotificationObserver {
+                      public ExtensionRegistryObserver {
  public:
   explicit PluginManager(content::BrowserContext* context);
   virtual ~PluginManager();
@@ -28,11 +29,6 @@ class PluginManager : public BrowserContextKeyedAPI,
   // BrowserContextKeyedAPI implementation.
   static BrowserContextKeyedAPIFactory<PluginManager>* GetFactoryInstance();
 
-  // content::NotificationObserver impelmentation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
  private:
   friend class BrowserContextKeyedAPIFactory<PluginManager>;
 
@@ -51,15 +47,25 @@ class PluginManager : public BrowserContextKeyedAPI,
 
   extensions::NaClModuleInfo::List::iterator FindNaClModule(const GURL& url);
 
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   // BrowserContextKeyedAPI implementation.
   static const char* service_name() { return "PluginManager"; }
   static const bool kServiceIsNULLWhileTesting = true;
 
   extensions::NaClModuleInfo::List nacl_module_list_;
 
-  content::NotificationRegistrar registrar_;
-
   Profile* profile_;
+
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
 };
 
 }  // namespace extensions
diff --git a/chrome/browser/extensions/user_script_master.cc b/chrome/browser/extensions/user_script_master.cc
index 972ea8b..9a72d8b 100644
--- a/chrome/browser/extensions/user_script_master.cc
+++ b/chrome/browser/extensions/user_script_master.cc
@@ -4,17 +4,11 @@
 
 #include "chrome/browser/extensions/user_script_master.h"
 
-#include <map>
 #include <string>
-#include <vector>
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
-#include "base/pickle.h"
-#include "base/stl_util.h"
-#include "base/strings/string_util.h"
-#include "base/threading/thread.h"
 #include "base/version.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ -25,10 +19,7 @@
 #include "chrome/common/extensions/manifest_handlers/content_scripts_handler.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
-#include "extensions/browser/extension_system.h"
-#include "extensions/common/extension.h"
-#include "extensions/common/extension_resource.h"
-#include "extensions/common/extension_set.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/common/file_util.h"
 #include "extensions/common/message_bundle.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -315,18 +306,14 @@ void UserScriptMaster::ScriptReloader::RunLoad(
           &ScriptReloader::NotifyMaster, this, Serialize(user_scripts)));
 }
 
-
 UserScriptMaster::UserScriptMaster(Profile* profile)
     : extensions_service_ready_(false),
       pending_load_(false),
-      profile_(profile) {
+      profile_(profile),
+      extension_registry_observer_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSIONS_READY,
                  content::Source<Profile>(profile_));
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
-  registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED,
-                 content::Source<Profile>(profile_));
   registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CREATED,
                  content::NotificationService::AllBrowserContextsAndSources());
 }
@@ -364,6 +351,52 @@ void UserScriptMaster::NewScriptsAvailable(base::SharedMemory* handle) {
   }
 }
 
+void UserScriptMaster::OnExtensionLoaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension) {
+  // Add any content scripts inside the extension.
+  extensions_info_[extension->id()] =
+      ExtensionSet::ExtensionPathAndDefaultLocale(
+          extension->path(), LocaleInfo::GetDefaultLocale(extension));
+  bool incognito_enabled = util::IsIncognitoEnabled(extension->id(), profile_);
+  const UserScriptList& scripts =
+      ContentScriptsInfo::GetContentScripts(extension);
+  for (UserScriptList::const_iterator iter = scripts.begin();
+       iter != scripts.end();
+       ++iter) {
+    user_scripts_.push_back(*iter);
+    user_scripts_.back().set_incognito_enabled(incognito_enabled);
+  }
+  if (extensions_service_ready_) {
+    if (script_reloader_.get()) {
+      pending_load_ = true;
+    } else {
+      StartLoad();
+    }
+  }
+}
+
+void UserScriptMaster::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  // Remove any content scripts.
+  extensions_info_.erase(extension->id());
+  UserScriptList new_user_scripts;
+  for (UserScriptList::iterator iter = user_scripts_.begin();
+       iter != user_scripts_.end();
+       ++iter) {
+    if (iter->extension_id() != extension->id())
+      new_user_scripts.push_back(*iter);
+  }
+  user_scripts_ = new_user_scripts;
+  if (script_reloader_.get()) {
+    pending_load_ = true;
+  } else {
+    StartLoad();
+  }
+}
+
 void UserScriptMaster::Observe(int type,
                                const content::NotificationSource& source,
                                const content::NotificationDetails& details) {
@@ -373,41 +406,6 @@ void UserScriptMaster::Observe(int type,
       extensions_service_ready_ = true;
       should_start_load = true;
       break;
-    case chrome::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
-      // Add any content scripts inside the extension.
-      const Extension* extension =
-          content::Details<const Extension>(details).ptr();
-      extensions_info_[extension->id()] =
-          ExtensionSet::ExtensionPathAndDefaultLocale(
-              extension->path(), LocaleInfo::GetDefaultLocale(extension));
-      bool incognito_enabled =
-          util::IsIncognitoEnabled(extension->id(), profile_);
-      const UserScriptList& scripts =
-          ContentScriptsInfo::GetContentScripts(extension);
-      for (UserScriptList::const_iterator iter = scripts.begin();
-           iter != scripts.end(); ++iter) {
-        user_scripts_.push_back(*iter);
-        user_scripts_.back().set_incognito_enabled(incognito_enabled);
-      }
-      if (extensions_service_ready_)
-        should_start_load = true;
-      break;
-    }
-    case chrome::NOTIFICATION_EXTENSION_UNLOADED_DEPRECATED: {
-      // Remove any content scripts.
-      const Extension* extension =
-          content::Details<UnloadedExtensionInfo>(details)->extension;
-      extensions_info_.erase(extension->id());
-      UserScriptList new_user_scripts;
-      for (UserScriptList::iterator iter = user_scripts_.begin();
-           iter != user_scripts_.end(); ++iter) {
-        if (iter->extension_id() != extension->id())
-          new_user_scripts.push_back(*iter);
-      }
-      user_scripts_ = new_user_scripts;
-      should_start_load = true;
-      break;
-    }
     case content::NOTIFICATION_RENDERER_PROCESS_CREATED: {
       content::RenderProcessHost* process =
           content::Source<content::RenderProcessHost>(source).ptr();
diff --git a/chrome/browser/extensions/user_script_master.h b/chrome/browser/extensions/user_script_master.h
index c764992..a7f9172 100644
--- a/chrome/browser/extensions/user_script_master.h
+++ b/chrome/browser/extensions/user_script_master.h
@@ -9,14 +9,12 @@
 #include <string>
 
 #include "base/compiler_specific.h"
-#include "base/files/file_path.h"
-#include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/shared_memory.h"
-#include "base/strings/string_piece.h"
+#include "base/scoped_observer.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry_observer.h"
 #include "extensions/common/extension_messages.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/user_script.h"
@@ -29,13 +27,16 @@ class Profile;
 
 namespace extensions {
 
+class ExtensionRegistry;
+
 typedef std::map<std::string, ExtensionSet::ExtensionPathAndDefaultLocale>
     ExtensionsInfo;
 
 // Manages a segment of shared memory that contains the user scripts the user
 // has installed.  Lives on the UI thread.
 class UserScriptMaster : public base::RefCountedThreadSafe<UserScriptMaster>,
-                         public content::NotificationObserver {
+                         public content::NotificationObserver,
+                         public ExtensionRegistryObserver {
  public:
   explicit UserScriptMaster(Profile* profile);
 
@@ -134,6 +135,14 @@ class UserScriptMaster : public base::RefCountedThreadSafe<UserScriptMaster>,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // ExtensionRegistryObserver implementation.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   // Sends the renderer process a new set of user scripts.
   void SendUpdate(content::RenderProcessHost* process,
                   base::SharedMemory* shared_memory);
@@ -165,6 +174,10 @@ class UserScriptMaster : public base::RefCountedThreadSafe<UserScriptMaster>,
   // The profile for which the scripts managed here are installed.
   Profile* profile_;
 
+  // Listen to extension load, unloaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(UserScriptMaster);
 };