Made it possible to tell whether an extension is being installed or updated.

chrome/browser/extensions/webstore_installer.cc

 // Copyright (c) 2012 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/webstore_installer.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
@@ skipping 229 matching lines @@
           installer->download_url() == download_item_->GetURL() &&
           installer->profile()->IsSameProfile(profile_)) {
         ReportFailure(kInstallCanceledError, FAILURE_REASON_CANCELLED);
       }
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_INSTALLED: {
       CHECK(profile_->IsSameProfile(content::Source<Profile>(source).ptr()));
       const Extension* extension =
-          content::Details<const Extension>(details).ptr();
+          content::Details<const InstalledExtensionInfo>(details)->extension;
       if (id_ == extension->id())
         ReportSuccess();
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_INSTALL_ERROR: {
       CrxInstaller* crx_installer = content::Source<CrxInstaller>(source).ptr();
       CHECK(crx_installer);
       if (!profile_->IsSameProfile(crx_installer->profile()))
         return;
@@ skipping 163 matching lines @@
 void WebstoreInstaller::ReportSuccess() {
   if (delegate_) {
     delegate_->OnExtensionInstallSuccess(id_);
     delegate_ = NULL;
   }
 
   Release();  // Balanced in Start().
 }
 
 }  // namespace extensions