Remove obsolete event from Bluetooth API.

chrome/common/extensions/api/experimental_bluetooth.idl

 // Copyright (c) 2012 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.
 
 // Bluetooth API.
 // TODO(bryeung): mark this API as ChromeOS only (see crbug.com/119398).
 
 namespace experimental.bluetooth {
   dictionary Device {
     // The address of the device, in the format 'XX:XX:XX:XX:XX:XX'.
@@ skipping 194 matching lines @@
   };
 
   interface Events {
     // Fired when the availability of bluetooth on the system changes.
     // |available| : True if bluetooth is available, false otherwise.
     static void onAvailabilityChanged(boolean available);
 
     // Fired when the power state of bluetooth on the system changes.
     // |powered| : True if bluetooth is powered, false otherwise.
     static void onPowerChanged(boolean has_power);
-
-    // Used to return discovered devices to the extension. Users should not
-    // add listeners to this event directly.
-    static void onDeviceDiscovered_(Device device);
   };
 };