Handle push resubscribes with no sender info (avoids DCHECK)

chrome/test/data/push_messaging/service_worker.js

Index: chrome/test/data/push_messaging/service_worker.js
diff --git a/chrome/test/data/push_messaging/service_worker.js b/chrome/test/data/push_messaging/service_worker.js
index 0e134855652b0d9035a39de5fed5584612bddb8b..d8c34929fcd9b5e7dbb4cd0f51fe9bce3c2cdf17 100644
--- a/chrome/test/data/push_messaging/service_worker.js
+++ b/chrome/test/data/push_messaging/service_worker.js
@@ -51,6 +51,9 @@ self.addEventListener('message', function handler (event) {
   };
   if (event.data.command == 'workerSubscribe') {
     pushSubscriptionOptions.applicationServerKey = kApplicationServerKey.buffer;
+  } else if (event.data.command == 'workerSubscribePushWithNumber') {

[harkness, 2016/11/02 18:48:12]

nit NumericKey?

[awdf, 2016/11/03 14:10:11]

Oops, this actually isn't called, (since it's one of those 'only support for
simplicity' cases, I didn't write explicit tests for it in the end). Removed.

[awdf, 2016/11/07 16:54:30]

Reinstated. Discussing with John we figured it's not such a bad idea to have
explicit tests for those yellow cases after all, in order to notice if something
changes, so long as there's a comment saying it's not ideal behaviour.

+    pushSubscriptionOptions.applicationServerKey =
+        new TextEncoder().encode('1234567890');
   } else if (event.data.command == 'workerSubscribeNoKey') {
     // Nothing to set up
   } else {