Bluetooth: add Device events, and cleanup JS API

chrome/test/data/extensions/api_test/bluetooth/discovery_callback/runtest.js

 // 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.
 
 var kExpectedDeviceNames = ["d1"];
 
 function testDiscovery() {
   chrome.test.assertEq(kExpectedDeviceNames.length,
       discoveredDevices.length);
   for (var i = 0; i < kExpectedDeviceNames.length; ++i) {
     chrome.test.assertEq(kExpectedDeviceNames[i],
         discoveredDevices[i].name);
   }
 
   chrome.test.succeed();
 }
 
 function startTests() {
   chrome.test.runTests([testDiscovery]);
 }
 
 function sendReady(callback) {
   chrome.test.sendMessage('ready', callback);
 }
 
-function stopDiscoveryAndContinue() {
-  chrome.bluetooth.stopDiscovery();
-  sendReady(startTests);
-}
-
 var discoveredDevices = [];
 function recordDevice(device) {
   discoveredDevices.push(device);
 }
 
+function stopDiscoveryAndContinue() {
+  chrome.bluetooth.stopDiscovery();
+  chrome.bluetooth.onDeviceAdded.removeListener(recordDevice);
+  sendReady(startTests);
+}
+
+chrome.bluetooth.onDeviceAdded.addListener(recordDevice);
 chrome.bluetooth.startDiscovery(
-    { deviceCallback:recordDevice },
     function() { sendReady(stopDiscoveryAndContinue); });