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

chrome/common/notification_type.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_NOTIFICATION_TYPE_H_
 #define CHROME_COMMON_NOTIFICATION_TYPE_H_
 
 // This file describes various types used to describe and filter notifications
 // that pass through the NotificationService.
 //
@@ skipping 817 matching lines @@
     // Sent by an extension to notify the browser about the results of a unit
     // test.
     EXTENSION_TEST_PASSED,
     EXTENSION_TEST_FAILED,
 
     // Sent when an bookmarks extensions API function was successfully invoked.
     // The source is the id of the extension that invoked the function, and the
     // 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)
     // is blocked by a privacy blacklist. The details are a const URLRequest,
     // and the source is a const ChromeURLRequestContext.
     BLACKLIST_NONVISUAL_RESOURCE_BLOCKED,
 
     // Debugging ---------------------------------------------------------------
 
     // TODO(mpcomplete): Sent to diagnose a bug. Remove when fixed.
@@ skipping 172 matching lines @@
 };
 
 inline bool operator==(NotificationType::Type a, NotificationType b) {
   return a == b.value;
 }
 inline bool operator!=(NotificationType::Type a, NotificationType b) {
   return a != b.value;
 }
 
 #endif  // CHROME_COMMON_NOTIFICATION_TYPE_H_