Bluetooth API: improve discovery

chrome/renderer/resources/extensions/experimental.bluetooth_custom_bindings.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.
 
 // Custom bindings for the Bluetooth API.
 
 var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 var sendRequest = require('sendRequest').sendRequest;
+var lastError = require('last_error');
 
 // Use custom bindings to create an undocumented event listener that will
 // receive events about device discovery and call the event listener that was
 // provided with the request to begin discovery.
 chromeHidden.registerCustomHook('experimental.bluetooth', function(api) {
   var apiFunctions = api.apiFunctions;
 
   chromeHidden.bluetooth = {};
-  chromeHidden.bluetooth.handler = null;
+  chromeHidden.bluetooth.deviceDiscoveredHandler = null;
   chromeHidden.bluetooth.onDeviceDiscovered =
       new chrome.Event("experimental.bluetooth.onDeviceDiscovered");
 
-  function deviceDiscoveredListener(device) {
-    if (chromeHidden.bluetooth.handler != null)
-      chromeHidden.bluetooth.handler(device);
+  function clearDeviceDiscoveredHandler() {
+    chromeHidden.bluetooth.onDeviceDiscovered.removeListener(
+        chromeHidden.bluetooth.deviceDiscoveredHandler);
+    chromeHidden.bluetooth.deviceDiscoveredHandler = null;
   }
-  chromeHidden.bluetooth.onDeviceDiscovered.addListener(
-      deviceDiscoveredListener);
 
-  apiFunctions.setHandleRequest('startDiscovery', function() {
-    var args = arguments;
-    if (args.length > 0 && args[0] && args[0].deviceCallback) {
-      chromeHidden.bluetooth.handler = args[0].deviceCallback;
-    }
-    sendRequest(this.name, args, this.definition.parameters);
-  });
-  apiFunctions.setHandleRequest('stopDiscovery', function() {
-    chromeHidden.bluetooth.handler = null;
-    sendRequest(this.name, arguments, this.definition.parameters);
-  });
+  apiFunctions.setHandleRequest('startDiscovery',
+      function() {
+        var args = arguments;
+        if (args.length > 0 && args[0] && args[0].deviceCallback) {
+          chromeHidden.bluetooth.deviceDiscoveredHandler =
+              args[0].deviceCallback;
+          chromeHidden.bluetooth.onDeviceDiscovered.addListener(
+              chromeHidden.bluetooth.deviceDiscoveredHandler);
+          sendRequest(this.name,
+                      args,
+                      this.definition.parameters,
+                      {customCallback:this.customCallback});
+        } else {
+          if (typeof(args[args.length-1]) == "function") {
+            var callback = args[args.length-1];
+            lastError.set("deviceCallback is required in the options object");
+            callback();
+            return;
+          }
+        }
+      });
+  apiFunctions.setCustomCallback('startDiscovery',
+      function(name, request, response) {
+        if (chrome.runtime.lastError) {
+          clearDeviceDiscoveredHandler();
+          return;
+        }
+      });
+  apiFunctions.setHandleRequest('stopDiscovery',
+      function() {
+        clearDeviceDiscoveredHandler();
+        sendRequest(this.name, arguments, this.definition.parameters);
+      });
 });