Implement WebBluetooth descriptor.readValue()

third_party/WebKit/LayoutTests/bluetooth/script-tests/descriptor/io-op-disconnect-called-before.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(
+                characteristic =>
+                    characteristic.getDescriptor(user_description.name))
+            .then(descriptor => {
+              gattServer.disconnect();
+              return assert_promise_rejects_with_message(
+                  descriptor.CALLS([readValue()]),
+                  new DOMException(
+                      'GATT Server is disconnected. Cannot perform GATT operations.',
+                      'NetworkError'));
+            });
+      });
+}, 'disconnect() called before FUNCTION_NAME. Reject with NetworkError.');