Teach EmbeddedWorkerInstance to create a process when it needs one.

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 91be6eb3972c7edba4ca85751aa0b2a2fd758452..57aa955b33c75967201e005abb0d1c9f9dfc9164 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -22,10 +22,9 @@ class ServiceWorkerContext {
   typedef base::Callback<void(bool success)> ResultCallback;
 
   // Equivalent to calling navigator.serviceWorker.register(script_url, {scope:
-  // pattern}) from a renderer in |source_process_id|, except that |pattern| is
-  // an absolute URL instead of relative to some current origin.  |callback| is
-  // passed true when the JS promise is fulfilled or false when the JS
-  // promise is rejected.
+  // pattern}) from a renderer, except that |pattern| is an absolute URL instead
+  // of relative to some current origin.  |callback| is passed true when the JS
+  // promise is fulfilled or false when the JS promise is rejected.
   //
   // The registration can fail if:
   //  * |script_url| is on a different origin from |pattern|
@@ -35,7 +34,6 @@ class ServiceWorkerContext {
   //  * Something unexpected goes wrong, like a renderer crash or a full disk.
   virtual void RegisterServiceWorker(const Scope& pattern,
                                      const GURL& script_url,
-                                     int source_process_id,
                                      const ResultCallback& callback) = 0;
 
   // Equivalent to calling navigator.serviceWorker.unregister(pattern) from a