Implement WebBluetooth getDescriptor[s]

third_party/WebKit/LayoutTests/bluetooth/script-tests/characteristic/characteristic-is-removed.js

+'use strict';
+promise_test(() => {
+  let val = new Uint8Array([1]);
+  return setBluetoothFakeAdapter('HeartRateAdapter')
+    .then(() => requestDeviceWithKeyDown({
+      filters: [{services: ['heart_rate']}],
+      optionalServices: ['generic_access']}))
+    .then(device => device.gatt.connect())
+    .then(gattServer => gattServer.getPrimaryService('generic_access'))
+    .then(service => service.getCharacteristic('gap.device_name'))
+    .then(characteristic => {
+      return setBluetoothFakeAdapter('MissingCharacteristicHeartRateAdapter')
+        .then(() => assert_promise_rejects_with_message(
+          characteristic.CALLS([
+              getDescriptor(user_description.name)|

[ortuno, 2016/12/07 08:05:12]

Also getDescriptors(user_description.name)[UUID]

[dougt, 2016/12/07 19:48:57]

Done.

+              getDescriptors()|
+              readValue()|
+              writeValue(val)|
+              startNotifications()]),
+          new DOMException(
+            'GATT Characteristic no longer exists.',
+            'InvalidStateError'),
+          'Characteristic got removed.'));
+    });
+}, 'Characteristic gets removed. Reject with InvalidStateError.');
+