Teach EmbeddedWorkerInstance to create a process when it needs one.

content/browser/service_worker/service_worker_register_job.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTER_JOB_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTER_JOB_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
@@ skipping 27 matching lines @@
                               ServiceWorkerVersion* version)>
       RegistrationCallback;
 
   CONTENT_EXPORT ServiceWorkerRegisterJob(
       base::WeakPtr<ServiceWorkerContextCore> context,
       const GURL& pattern,
       const GURL& script_url);
   virtual ~ServiceWorkerRegisterJob();
 
   // Registers a callback to be called when the promise would resolve (whether
-  // successfully or not). Multiple callbacks may be registered. |process_id| is
-  // added via AddProcessToWorker to the ServiceWorkerVersion created by the
-  // registration job.
+  // successfully or not). Multiple callbacks may be registered. If |process_id|
+  // is not -1, it's used to create the Service Worker instance if there are no
+  // other clients.  If it is -1, the registration must have been started from
+  // ServiceWorkerContextWrapper::RegisterServiceWorker(browser_context), and
+  // that browser_context will be used to create a process if there are no
+  // existing clients.
   void AddCallback(const RegistrationCallback& callback, int process_id);
 
   // ServiceWorkerRegisterJobBase implementation:
   virtual void Start() OVERRIDE;
   virtual bool Equals(ServiceWorkerRegisterJobBase* job) OVERRIDE;
   virtual RegistrationJobType GetType() OVERRIDE;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerRegisterJobAndProviderHostTest,
                            AssociatePendingVersionToDocuments);
@@ skipping 59 matching lines @@
   scoped_refptr<ServiceWorkerRegistration> promise_resolved_registration_;
   scoped_refptr<ServiceWorkerVersion> promise_resolved_version_;
   base::WeakPtrFactory<ServiceWorkerRegisterJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerRegisterJob);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_REGISTER_JOB_H_