First pass at experimental omnibox API. There are plenty of rough edges and

chrome/common/notification_type.h

Index: chrome/common/notification_type.h
diff --git a/chrome/common/notification_type.h b/chrome/common/notification_type.h
index de9efcb5c8bf87e7211445a9c7d3c5794a8dc762..68a64b1d701901a4cd0cdf4b6c8f9b2fd5753c30 100644
--- a/chrome/common/notification_type.h
+++ b/chrome/common/notification_type.h
@@ -835,6 +835,11 @@ class NotificationType {
     // details are a pointer to the const BookmarksFunction in question.
     EXTENSION_BOOKMARKS_API_INVOKED,
 
+    // Sent when an omnibox extension has sent back omnibox suggestions. The
+    // source is the profile, and the details are a
+    // std::pair<int suggest_id, ListValue suggestions_array>
+    EXTENSION_OMNIBOX_SUGGESTIONS_READY,
+
     // Privacy Blacklist -------------------------------------------------------
 
     // Sent on the IO thread when a non-visual resource (like a cookie)