Teach EmbeddedWorkerInstance to create a process when it needs one.

content/browser/service_worker/service_worker_version.h

Index: content/browser/service_worker/service_worker_version.h
diff --git a/content/browser/service_worker/service_worker_version.h b/content/browser/service_worker/service_worker_version.h
index dcdf1b62f33d09a1d86e477103265213757ffcb8..53dc0f091984715fe9c9810ac392794f07844f86 100644
--- a/content/browser/service_worker/service_worker_version.h
+++ b/content/browser/service_worker/service_worker_version.h
@@ -115,7 +115,11 @@ class CONTENT_EXPORT ServiceWorkerVersion
 
   // Starts an embedded worker for this version.
   // This returns OK (success) if the worker is already running.
-  void StartWorker(const StatusCallback& callback);
+  // |potential_process_ids| is a list of processes in which to start the
+  // worker.
+  void StartWorker(
+      const StatusCallback& callback,
+      const std::vector<int>& potential_process_ids = std::vector<int>());

[kinuko, 2014/04/28 06:58:16]

Again, no optional parameters in chromium...  Could we have another method like,
StartWorkerWithCandidateProcesses() (as function overloading is not really
preferred either), which takes process_ids param?  StartWorker can internally
call it then.

[Jeffrey Yasskin, 2014/04/28 20:47:40]

Sure, done.

 
   // Starts an embedded worker for this version.
   // This returns OK (success) if the worker is already stopped.
@@ -212,6 +216,12 @@ class CONTENT_EXPORT ServiceWorkerVersion
 
   virtual ~ServiceWorkerVersion();
 
+  void RunStartWorkerCallbacksOnError(ServiceWorkerStatusCode status);
+
+  void DispatchInstallEventAfterStartWorker(int active_version_id,
+                                            const StatusCallback& callback);
+  void DispatchActivateEventAfterStartWorker(const StatusCallback& callback);
+
   // Message handlers.
   void OnGetClientDocuments(int request_id);
   void OnActivateEventFinished(int request_id,