Remove NOTIFICATION_EXTENSION_ENABLED.

extensions/browser/extension_registry_observer.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_REGISTRY_OBSERVER_H_
 #define EXTENSIONS_BROWSER_EXTENSION_REGISTRY_OBSERVER_H_
 
 #include "extensions/browser/uninstall_reason.h"
 #include "extensions/common/extension.h"
 
@@ skipping 11 matching lines @@
 class ExtensionRegistryObserver {
  public:
   virtual ~ExtensionRegistryObserver() {}
 
   // Called after an extension is loaded. The extension will exclusively exist
   // in the enabled_extensions set of ExtensionRegistry.
   virtual void OnExtensionLoaded(
       content::BrowserContext* browser_context,
       const Extension* extension) {}
 
+  // Called when an extension is enabled. Under most circumstances, listeners
+  // will want to use OnExtensionLoaded(). This is only called when the "Enable"
+  // button is hit in the extensions tab.
+  virtual void OnExtensionEnabled(content::BrowserContext* browser_context,
+                                  const Extension* extension) {}
+
   // Called after an extension is loaded and all necessary browser state is
   // initialized to support the start of the extension's child process.
   virtual void OnExtensionReady(content::BrowserContext* browser_context,
                                 const Extension* extension) {}
 
   // Called after an extension is unloaded. The extension no longer exists in
   // the set |ExtensionRegistry::enabled_extensions()|, but it can still be a
   // member of one of the other sets, like disabled, blacklisted or terminated.
   virtual void OnExtensionUnloaded(content::BrowserContext* browser_context,
                                    const Extension* extension,
@@ skipping 31 matching lines @@
                                       const Extension* extension,
                                       UninstallReason reason) {}
 
   // Notifies observers that the observed object is going away.
   virtual void OnShutdown(ExtensionRegistry* registry) {}
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_REGISTRY_OBSERVER_H_