Add PrerenderStatusEvent on Prerenders

chrome/browser/prerender/prerender_contents.h

Index: chrome/browser/prerender/prerender_contents.h
diff --git a/chrome/browser/prerender/prerender_contents.h b/chrome/browser/prerender/prerender_contents.h
index bd0de98ea5c5f5a66f1d034a6fbf585128aacb4c..7d55e2217dc4619ee019f1e8c823cba393c65ffa 100644
--- a/chrome/browser/prerender/prerender_contents.h
+++ b/chrome/browser/prerender/prerender_contents.h
@@ -112,6 +112,7 @@ class PrerenderContents : public content::NotificationObserver,
   // page should be part of.
   virtual void StartPrerendering(
       int creator_child_id,
+      int prerender_id,
       const gfx::Size& size,
       content::SessionStorageNamespace* session_storage_namespace,
       bool is_control_group);
@@ -380,6 +381,9 @@ class PrerenderContents : public content::NotificationObserver,
   // The process that created the child id.
   int creator_child_id_;
 
+  // The prerender id from the launcher.
+  int prerender_id_;
+
   // The size of the WebView from the launching page.
   gfx::Size size_;