Register a Service Worker when an extension is enabled.

extensions/browser/process_manager.h

Index: extensions/browser/process_manager.h
diff --git a/extensions/browser/process_manager.h b/extensions/browser/process_manager.h
index 664c9420fde504a05d071e6de9a9a232722b57fa..a9e98da57464e55d063737252a4b928e8051fda0 100644
--- a/extensions/browser/process_manager.h
+++ b/extensions/browser/process_manager.h
@@ -61,8 +61,10 @@ class ProcessManager : public content::NotificationObserver {
   // displayed anywhere.  Returns false if no background host can be created,
   // for example for hosted apps and extensions that aren't enabled in
   // Incognito.
-  virtual bool CreateBackgroundHost(const Extension* extension,
-                                    const GURL& url);
+  virtual bool CreateBackgroundHost(
+      const Extension* extension,
+      const GURL& url,
+      const base::Closure& continuation = base::Closure());
 
   // Gets the ExtensionHost for the background page for an extension, or NULL if
   // the extension isn't running or doesn't have a background page.