Revert "app_shell: Add experimental shellPrivate extension API"

extensions/common/api/shell_private.idl

Index: extensions/common/api/shell_private.idl
diff --git a/extensions/common/api/shell_private.idl b/extensions/common/api/shell_private.idl
deleted file mode 100644
index f964c29eced1aca1e689d3eb164c5a2dcbd8051a..0000000000000000000000000000000000000000
--- a/extensions/common/api/shell_private.idl
+++ /dev/null
@@ -1,12 +0,0 @@
-// 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.
-
-// <code>chrome.shellPrivate</code> API with experimental APIs for app_shell.
-[nodoc] namespace shellPrivate {
-
-  interface Functions {
-    // Prints "hello" to the Chrome log.
-    static void printHello();
-  };
-};