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..2f687398c072b62f83ae3f37691e0be87dd3a45d 100644
--- a/content/browser/service_worker/service_worker_version.h
+++ b/content/browser/service_worker/service_worker_version.h
@@ -115,7 +115,10 @@ 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);
 
   // Starts an embedded worker for this version.
   // This returns OK (success) if the worker is already stopped.
@@ -138,8 +141,10 @@ class CONTENT_EXPORT ServiceWorkerVersion
   // the version's status to INSTALLING.
   // Upon completion, the version's status will be changed to INSTALLED
   // on success, or back to NEW on failure.
+  // |second_call| is for internal use.
   void DispatchInstallEvent(int active_version_id,
-                            const StatusCallback& callback);
+                            const StatusCallback& callback,
+                            bool second_call = false);
 
   // Sends activate event to the associated embedded worker and asynchronously
   // calls |callback| when it errors out or it gets response from the worker
@@ -149,7 +154,9 @@ class CONTENT_EXPORT ServiceWorkerVersion
   // the version's status to ACTIVATING.
   // Upon completion, the version's status will be changed to ACTIVE
   // on success, or back to INSTALLED on failure.
-  void DispatchActivateEvent(const StatusCallback& callback);
+  // |second_call| is for internal use.
+  void DispatchActivateEvent(const StatusCallback& callback,
+                             bool second_call = false);
 
   // Sends fetch event to the associated embedded worker and calls
   // |callback| with the response from the worker.
@@ -212,6 +219,8 @@ class CONTENT_EXPORT ServiceWorkerVersion
 
   virtual ~ServiceWorkerVersion();
 
+  void RunStartWorkerCallbacksOnError(ServiceWorkerStatusCode status);
+
   // Message handlers.
   void OnGetClientDocuments(int request_id);
   void OnActivateEventFinished(int request_id,