Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/bookmarks/bookmarks_api.cc

Index: chrome/browser/extensions/api/bookmarks/bookmarks_api.cc
diff --git a/chrome/browser/extensions/api/bookmarks/bookmarks_api.cc b/chrome/browser/extensions/api/bookmarks/bookmarks_api.cc
index 2e08bda3614535aa7fe3b05b35f42faccf96a21e..8db4a81a4e511939d4c105e9d43eb683628e8e39 100644
--- a/chrome/browser/extensions/api/bookmarks/bookmarks_api.cc
+++ b/chrome/browser/extensions/api/bookmarks/bookmarks_api.cc
@@ -258,8 +258,8 @@ void BookmarkEventRouter::DispatchEvent(
     scoped_ptr<base::ListValue> event_args) {
   EventRouter* event_router = EventRouter::Get(browser_context_);
   if (event_router) {
-    event_router->BroadcastEvent(
-        make_scoped_ptr(new extensions::Event(event_name, event_args.Pass())));
+    event_router->BroadcastEvent(make_scoped_ptr(new extensions::Event(
+        extensions::events::UNKNOWN, event_name, event_args.Pass())));
   }
 }