Prerender: Confirm ServiceWorkers are invoked for NoState Prefetch

content/public/browser/service_worker_context.h

Index: content/public/browser/service_worker_context.h
diff --git a/content/public/browser/service_worker_context.h b/content/public/browser/service_worker_context.h
index c095f9d1314c7fe028441bb19479c2f73d4fc99e..e1c97a735a94f9ebe617fbd17a0c399ae8e99b68 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -125,6 +125,12 @@ class ServiceWorkerContext {
   // This function can be called from any thread.
   virtual void StopAllServiceWorkersForOrigin(const GURL& origin) = 0;
 
+  // As above, but |callback| is exectued when a running worker is stopped. If

[pasko, 2017/01/02 18:15:36]

nit: s/exectued/executed/

[mattcary, 2017/01/03 09:00:03]

Done.

+  // there is no running worker, |callback| will never be executed.

[pasko, 2017/01/02 18:15:36]

My personal preference would be with _always_ invoking the callback, with status
depending on whether there was a SW running.

Not my call though, up to content owners.

[mattcary, 2017/01/03 09:00:03]

Given its current use in a test these semantics work fine. 

Adding more information for speculative future use makes me nervous for several
reasons: I was not really interested in widening the API by adding a public
status enumeration (or exposing the existing internal status enum). Also, there
seems to be a range of behavior depending on the state of
ServiceWorkerVersion---exposing a status will probably necessarily leak the
implementation (eg, a ServiceWorkerVersion that exists but which is already
stopped, etc).

+  virtual void StopAllServiceWorkersForOriginWithCallback(
+      const GURL& origin,
+      const base::Closure& callback) = 0;
+
   // Stops all running service workers and unregisters all service worker
   // registrations. This method is used in LayoutTests to make sure that the
   // existing service worker will not affect the succeeding tests.