Disable off-store extension installs by default.

chrome/browser/download/chrome_download_manager_delegate.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/download/chrome_download_manager_delegate.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 79 matching lines @@
 bool ChromeDownloadManagerDelegate::IsExtensionDownload(
     const DownloadItem* item) {
   if (item->PromptUserForSaveLocation())
     return false;
 
   if ((item->GetMimeType() != Extension::kMimeType) &&
       !UserScript::IsURLUserScript(item->GetURL(), item->GetMimeType())) {
     return false;
   }
 
-  return download_crx_util::ShouldOpenExtensionDownload(*item);
+  Profile* profile = Profile::FromBrowserContext(item->GetBrowserContext());
+  return download_crx_util::ShouldOpenExtensionDownload(
+      profile->GetExtensionService(), *item);
 }
 
 void ChromeDownloadManagerDelegate::SetDownloadManager(DownloadManager* dm) {
   download_manager_ = dm;
   download_history_.reset(new DownloadHistory(profile_));
   download_history_->Load(
       base::Bind(&DownloadManager::OnPersistentStoreQueryComplete,
                  base::Unretained(dm)));
 }
 
@@ skipping 608 matching lines @@
     int32 download_id, int64 db_handle) {
   // It's not immediately obvious, but HistoryBackend::CreateDownload() can
   // call this function with an invalid |db_handle|. For instance, this can
   // happen when the history database is offline. We cannot have multiple
   // DownloadItems with the same invalid db_handle, so we need to assign a
   // unique |db_handle| here.
   if (db_handle == DownloadItem::kUninitializedHandle)
     db_handle = download_history_->GetNextFakeDbHandle();
   download_manager_->OnItemAddedToPersistentStore(download_id, db_handle);
 }