Introduce background.scripts feature for extension manifests.

This optimizes for the common use case where background pages
just include a reference to one or more script files and no
additional HTML.

BUG=107791


Review URL: http://codereview.chromium.org/9150008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@117110 0039d316-1c4b-4281-b951-d872f2087c98
void TestingAutomationProvider::GetCookiesJSON(
    DictionaryValue* args, IPC::Message* reply_message) {
  automation_util::GetCookiesJSON(this, args, reply_message);
}

void TestingAutomationProvider::GetCookiesJSON(
    DictionaryValue* args, IPC::Message* reply_message) {
  automation_util::GetCookiesJSON(this, args, reply_message);
}
