Add testing for subscription from service workers

content/child/push_messaging/push_provider.cc

Index: content/child/push_messaging/push_provider.cc
diff --git a/content/child/push_messaging/push_provider.cc b/content/child/push_messaging/push_provider.cc
index 254d855106bd9466a87c7009f3dff7f01609c275..a9e79f5cb7db4b8391c6f1623c559ae0476210c6 100644
--- a/content/child/push_messaging/push_provider.cc
+++ b/content/child/push_messaging/push_provider.cc
@@ -77,7 +77,10 @@ void PushProvider::subscribe(
       GetServiceWorkerRegistrationId(service_worker_registration);
   PushSubscriptionOptions content_options;
   content_options.user_visible_only = options.userVisibleOnly;
-  content_options.sender_info = options.applicationServerKey.utf8();
+
+  // Just treat the server key as a string of bytes and pass it to the push
+  // service.
+  content_options.sender_info = options.applicationServerKey.latin1();
   thread_safe_sender_->Send(new PushMessagingHostMsg_SubscribeFromWorker(
       request_id, service_worker_registration_id, content_options));
 }