Implement create attribute API functions for BTLE.

chrome/test/data/extensions/api_test/bluetooth_low_energy/create_descriptor/runtest.js

+// 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.
+
+function failOnError(result) {
+  if (chrome.runtime.lastError || !result) {
+    chrome.test.fail(chrome.runtime.lastError.message);
+    return true;
+  }
+  return false;
+}
+
+function failOnSuccess() {
+  if (!chrome.runtime.lastError) {
+    chrome.test.fail('lastError not set, operation succeeded.');
+    return true;
+  }
+  return false;
+}
+
+var service = { uuid: '00001234-0000-1000-8000-00805f9b34fb', isPrimary: true };
+chrome.bluetoothLowEnergy.createService(service, function(serviceId) {
+  if (failOnError(serviceId))
+    return;
+
+  var characteristic = { uuid: '00001234-0000-1000-8000-00805f9b34fa',
+    properties: ['read']};
+  chrome.bluetoothLowEnergy.createCharacteristic(characteristic, serviceId,
+      function(characteristicId) {
+    if (failOnError(characteristicId))
+      return;
+
+    var descriptor = { uuid: '00001234-0000-1000-8000-00805f9b34fc' };
+    // Invalid characteristic ID.
+    chrome.bluetoothLowEnergy.createDescriptor(descriptor,
+        'invalidCharacteristicId', function(descriptorId) {
+      if (failOnSuccess())
+        return;
+
+      // Valid characteristic ID.
+      chrome.bluetoothLowEnergy.createDescriptor(descriptor, characteristicId,
+          function(descriptorId) {
+        if (failOnError(descriptorId))
+          return;
+
+        chrome.test.succeed();
+      });
+    });
+  });
+});