Sanity tweaks to the extension blacklist: check all extensions at once on

chrome/browser/extensions/extension_install_ui_default.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/extension_install_ui_default.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/api/infobars/confirm_infobar_delegate.h"
@@ skipping 187 matching lines @@
 }
 
 void ExtensionInstallUIDefault::OnInstallFailure(
     const extensions::CrxInstallerError& error) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (disable_failure_ui_for_tests || skip_post_install_ui_)
     return;
 
   Browser* browser = chrome::FindLastActiveWithProfile(profile_,
       chrome::GetActiveDesktop());
+  if (!browser)  // unit tests
+    return;
   WebContents* web_contents =
       browser->tab_strip_model()->GetActiveWebContents();
   if (!web_contents)
     return;
   ErrorInfobarDelegate::Create(InfoBarService::FromWebContents(web_contents),
                                browser, error);
 }
 
 void ExtensionInstallUIDefault::SetSkipPostInstallUI(bool skip_ui) {
   skip_post_install_ui_ = skip_ui;
@@ skipping 44 matching lines @@
   return new ExtensionInstallPrompt(web_contents);
 }
 
 // static
 ExtensionInstallPrompt* ExtensionInstallUI::CreateInstallPromptWithProfile(
     Profile* profile) {
   Browser* browser = chrome::FindLastActiveWithProfile(profile,
       chrome::GetActiveDesktop());
   return CreateInstallPromptWithBrowser(browser);
 }