Introduce background.scripts feature for extension manifests.

chrome/browser/extensions/background_scripts_apitest.cc

Index: chrome/browser/extensions/background_scripts_apitest.cc
diff --git a/chrome/browser/extensions/background_scripts_apitest.cc b/chrome/browser/extensions/background_scripts_apitest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..292f6bc9cc81d688d0b4b1ced097f10d9db30531
--- /dev/null
+++ b/chrome/browser/extensions/background_scripts_apitest.cc
@@ -0,0 +1,9 @@
+// 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_apitest.h"
+
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, BackgroundScripts) {
+  ASSERT_TRUE(RunExtensionTest("background_scripts")) << message_;
+}