Remove InstallTracker's extension installed, uninstalled observers.

chrome/browser/extensions/install_tracker.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_INSTALL_TRACKER_H_
 #define CHROME_BROWSER_EXTENSIONS_INSTALL_TRACKER_H_
 
 #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;
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 class ExtensionPrefs;
-class ExtensionRegistry;
 
 class InstallTracker : public KeyedService,
-                       public content::NotificationObserver,
-                       public ExtensionRegistryObserver {
+                       public content::NotificationObserver {
  public:
   InstallTracker(Profile* profile,
                  extensions::ExtensionPrefs* prefs);
   virtual ~InstallTracker();
 
   static InstallTracker* Get(content::BrowserContext* context);
 
   void AddObserver(InstallObserver* observer);
   void RemoveObserver(InstallObserver* observer);
 
   void OnBeginExtensionInstall(
       const InstallObserver::ExtensionInstallParams& params);
   void OnBeginExtensionDownload(const std::string& extension_id);
   void OnDownloadProgress(const std::string& extension_id,
                           int percent_downloaded);
   void OnBeginCrxInstall(const std::string& extension_id);
   void OnFinishCrxInstall(const std::string& extension_id, bool success);
   void OnInstallFailure(const std::string& extension_id);
 
+  // NOTE(limasdf): For extension [un]load and [un]installed, use
+  //                ExtensionRegistryObserver.
+
   // Overriddes for KeyedService.
   virtual void Shutdown() OVERRIDE;
 
  private:
   void OnAppsReordered();
 
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
-  // ExtensionRegistryObserver implementation.
-  virtual void OnExtensionWillBeInstalled(
-      content::BrowserContext* browser_context,
-      const Extension* extension,
-      bool is_update,
-      bool from_ephemeral,
-      const std::string& old_name) OVERRIDE;
-
   ObserverList<InstallObserver> observers_;
   content::NotificationRegistrar registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
-  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
-      extension_registry_observer_;
-
   DISALLOW_COPY_AND_ASSIGN(InstallTracker);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_INSTALL_TRACKER_H_