bluetooth: Improve error message for retrieving Descriptors when disconnecting

third_party/WebKit/LayoutTests/bluetooth/script-tests/characteristic/descriptor-disconnect-called-during-success.js

+'use strict';
+promise_test(
+    () => {
+      let val = new Uint8Array([1]);
+      return setBluetoothFakeAdapter('DisconnectingHealthThermometerAdapter')
+          .then(
+              () => requestDeviceWithKeyDown(
+                  {filters: [{services: ['health_thermometer']}]}))
+          .then(device => device.gatt.connect())
+          .then(gattServer => {
+            return gattServer.getPrimaryService('health_thermometer')
+                .then(
+                    service =>
+                        service.getCharacteristic('measurement_interval'))
+                .then(measurement_interval => {
+                  let promise = assert_promise_rejects_with_message(
+                      measurement_interval.CALLS(
+                          [getDescriptor(user_description.name) |
+                           getDescriptors(user_description.name)[UUID] |
+                           getDescriptors()]),
+                      new DOMException(
+                          'GATT Server is disconnected. Cannot retrieve descriptors. ' +
+                              '(Re)connect first with `device.gatt.connect`.',
+                          'NetworkError'));
+                  gattServer.disconnect();
+                  return promise;
+                });
+          });
+    },
+    'disconnect() called during a FUNCTION_NAME call that succeeds. ' +
+        'Reject with NetworkError.');