Notify launcher page with onTransitionChanged event

chrome/common/extensions/api/launcher_page.idl

Index: chrome/common/extensions/api/launcher_page.idl
diff --git a/chrome/common/extensions/api/launcher_page.idl b/chrome/common/extensions/api/launcher_page.idl
new file mode 100644
index 0000000000000000000000000000000000000000..feda60b439c9dcf8d62970ef50c444642f271749
--- /dev/null
+++ b/chrome/common/extensions/api/launcher_page.idl
@@ -0,0 +1,11 @@
+// Copyright 2014 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.
+
+// The <code>chrome.launcherPage</code> API provides launcher pages in the App
+// Launcher with the capabilities and events they need.
+namespace launcherPage {
+  interface Events {
+    static void onTransitionChanged(double progress);
+  };
+};