bluetooth: Introduce helper function for requesting a disconnection

third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js

Index: third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js
diff --git a/third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js b/third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js
index fd9719a503127e16868524ab3d36bc68be4464de..bc1e607c11cdd06824070dc647ec4c606f08a13f 100644
--- a/third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js
+++ b/third_party/WebKit/LayoutTests/resources/bluetooth/bluetooth-helpers.js
@@ -318,6 +318,22 @@ class EventCatcher {
   }
 }
 
+// Returns a function that when called returns a promise that resolves when
+// the device has disconnected. Example:
+// device.gatt.connect()
+//   .then(gatt => get_request_disconnection(gatt))
+//   .then(requestDisconnection => requestDisconnection())
+//   .then(() => // device is now disconnected)
+function get_request_disconnection(gattServer) {
+  return gattServer.getPrimaryService(request_disconnection_service_uuid)
+    .then(service => service.getCharacteristic(request_disconnection_characteristic_uuid))
+    .then(characteristic => {
+      // TODO(crbug.com/543466): Wrap in assert_promise_rejects_with_message()
+      // once connection is required for writeValue to succeed.
+      return () => characteristic.writeValue(new Uint8Array([0]));
+    });
+}
+
 function generateRequestDeviceArgsWithServices(services = ['heart_rate']) {
   return [{
     filters: [{ services: services }]