Use process-per-app-instance for hosted apps without background permission.

content/common/content_notification_types.h

Index: content/common/content_notification_types.h
diff --git a/content/common/content_notification_types.h b/content/common/content_notification_types.h
index 76006adf16d1ac35469f01a8f4955aa2e021c337..b513e352e9d39e9c5ec7c1bee99e958441640e7c 100644
--- a/content/common/content_notification_types.h
+++ b/content/common/content_notification_types.h
@@ -369,6 +369,10 @@ enum {
   // the new state is "visible."
   NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
 
+  // Sent from ~SiteInstance.  The source is the SiteInstance, and the details
+  // are unused.
+  NOTIFICATION_SITE_INSTANCE_DELETED,
+
   // The focused element inside a page has changed.  The source is the
   // TabContents containing the render view host for the page. The details is
   // a Details<const bool> that indicates whether or not an editable node was