Disable off-store extension installs by default.

chrome/browser/extensions/bundle_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/bundle_installer.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 138 matching lines @@
   }
 
   // Start each WebstoreInstaller.
   for (ItemMap::iterator i = items_.begin(); i != items_.end(); ++i) {
     if (i->second.state != Item::STATE_PENDING)
       continue;
 
     // Since we've already confirmed the permissions, create an approval that
     // lets CrxInstaller bypass the prompt.
     scoped_ptr<WebstoreInstaller::Approval> approval(
-        new WebstoreInstaller::Approval);
-    approval->extension_id = i->first;
-    approval->profile = profile_;
-    approval->parsed_manifest.reset(parsed_manifests_[i->first]->DeepCopy());
+        WebstoreInstaller::Approval::CreateWithNoInstallPrompt(
+            profile_,
+            i->first,
+            scoped_ptr<base::DictionaryValue>(
+                parsed_manifests_[i->first]->DeepCopy())));
     approval->use_app_installed_bubble = false;
     approval->skip_post_install_ui = true;
 
     scoped_refptr<WebstoreInstaller> installer = new WebstoreInstaller(
         profile_,
         this,
         controller,
         i->first,
         approval.Pass(),
         WebstoreInstaller::FLAG_NONE);
@@ skipping 161 matching lines @@
 void BundleInstaller::OnBrowserAdded(const Browser* browser) {}
 
 void BundleInstaller::OnBrowserRemoved(const Browser* browser) {
   if (browser_ == browser)
     browser_ = NULL;
 }
 
 void BundleInstaller::OnBrowserSetLastActive(const Browser* browser) {}
 
 }  // namespace extensions