Implement WebBluetooth getDescriptor[s]

third_party/WebKit/LayoutTests/bluetooth/script-tests/characteristic/descriptor-garbage-collection-ran-during-success.js

+'use strict';
+promise_test(() => {
+  let promise;
+  return setBluetoothFakeAdapter('DisconnectingHealthThermometerAdapter')
+    .then(() => requestDeviceWithKeyDown({
+      filters: [{services: ['health_thermometer']}]}))
+    .then(device => device.gatt.connect())
+    .then(gattServer => gattServer.getPrimaryService('health_thermometer'))
+    .then(service => service.getCharacteristic('measurement_interval'))
+    .then(characteristic => {
+      promise = assert_promise_rejects_with_message(
+        characteristic.CALLS([
+          getDescriptor(user_description.name)|
+          getDescriptors()|
+          getDescriptors(user_description.name)[UUID]]),
+        new DOMException(
+          'GATT Server disconnected while performing a GATT operation.',
+          'NetworkError'));
+      // Disconnect called to clear attributeInstanceMap and allow the
+      // object to get garbage collected.
+      characteristic.service.device.gatt.disconnect();
+    })
+    .then(runGarbageCollection)
+    .then(() => promise);
+}, 'Garbage Collection ran during a FUNCTION_NAME call that succeeds. ' +
+   'Should not crash.');