Expose BudgetState interface to Workers.

third_party/WebKit/LayoutTests/http/tests/budget/resources/instrumentation-service-worker.js

 // Allows a document to exercise the Budget API within a service worker by sending commands.
 
 self.addEventListener('message', function(workerEvent) {
   port = workerEvent.data;
 
   // Listen to incoming commands on the message port.
   port.onmessage = function(event) {
     if (typeof event.data != 'object' || !event.data.command)
       return;
     var options = event.data.options || {};
@@ skipping 36 matching lines @@
         break;
 
       case 'checkInterfaces':
         let success = false;
         let message = "";
         try {
           success = 'BudgetService' in self &&
               WorkerNavigator.prototype.hasOwnProperty('budget') &&
               BudgetService.prototype.hasOwnProperty('getCost') &&
               BudgetService.prototype.hasOwnProperty('getBudget') &&
-              BudgetService.prototype.hasOwnProperty('reserve')
+              BudgetService.prototype.hasOwnProperty('reserve') &&
+              'BudgetState' in self &&
+              BudgetState.prototype.hasOwnProperty('budgetAt') &&
+              BudgetState.prototype.hasOwnProperty('time');

[Peter Beverloo, 2016/12/14 11:37:08]

Something that crossed my mind - we have no tests in either dedicated or shared
workers right now. It'd be cool to at least have some sort of smoke test to
verify that something works.

[harkness, 2016/12/14 13:48:58]

Sure, I can look into adding something for one or both of those.

         } catch(err) {
           message = err.message;
         }
         port.postMessage({
           command: event.data.command,
           success: success,
           message: message});
         break;
 
       default:
@@ skipping 10 matching lines @@
 
 function makeErrorHandler(command) {
   return function(error) {
     var errorMessage = error ? error.message : 'unknown error';
     port.postMessage({
       command: command,
       success: false,
       errorMessage: errorMessage });
   };
 }