Fix case where install puts two copies of the extension toolbar on the shelf.

chrome/browser/extensions/extension_shelf_model.cc

 // Copyright (c) 2009 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 "chrome/browser/extensions/extension_shelf_model.h"
 
 #include "chrome/browser/browser.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/notification_service.h"
 
 /////////////////////////////
 
 ExtensionShelfModel::ExtensionShelfModel(Browser* browser)
     : browser_(browser), ready_(false) {
   // Watch extensions loaded and unloaded notifications.
-  registrar_.Add(this, NotificationType::EXTENSION_INSTALLED,
-                 NotificationService::AllSources());
   registrar_.Add(this, NotificationType::EXTENSION_UNLOADED,
                  NotificationService::AllSources());
   registrar_.Add(this, NotificationType::EXTENSIONS_LOADED,
                  NotificationService::AllSources());
   registrar_.Add(this, NotificationType::EXTENSIONS_READY,
                  NotificationService::AllSources());
 
   // Add any already-loaded extensions now, since we missed the notification for
   // those.
   ExtensionsService* service = browser_->profile()->GetExtensionsService();
@@ skipping 71 matching lines @@
 }
 
 ExtensionHost* ExtensionShelfModel::ToolstripAt(int index) {
   return toolstrips_[index];
 }
 
 void ExtensionShelfModel::Observe(NotificationType type,
                                   const NotificationSource& source,
                                   const NotificationDetails& details) {
   switch (type.value) {
-    case NotificationType::EXTENSION_INSTALLED:
-      if (ready_) {
-        AddExtension(Details<Extension>(details).ptr());
-        UpdatePrefs();
-      }
-      break;
     case NotificationType::EXTENSIONS_LOADED:
       if (ready_)
         AddExtensions(Details<ExtensionList>(details).ptr());
       break;
     case NotificationType::EXTENSION_UNLOADED:
       RemoveExtension(Details<Extension>(details).ptr());
       break;
     case NotificationType::EXTENSIONS_READY:
       AddExtensions(browser_->profile()->GetExtensionsService()->extensions());
       SortToolstrips();
@@ skipping 94 matching lines @@
   // Any toolstrips remaining in |copy| were somehow missing from the prefs,
   // so just append them to the end.
   for (ExtensionToolstrips::iterator toolstrip = copy.begin();
       toolstrip != copy.end(); ++toolstrip) {
     toolstrips_.push_back(*toolstrip);
   }
 
   FOR_EACH_OBSERVER(ExtensionShelfModelObserver, observers_,
                     ShelfModelReloaded());
 }