bluetooth: Add device list retrieval for chrome://bluetooth-internals

device/bluetooth/public/interfaces/adapter.mojom

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module bluetooth.mojom;
+
+struct DeviceInfo {
+  string? name;
+  string name_for_display;
+  string id;
+  string address;
+};
+
+interface Adapter {
+  // Retrieves the list of the devices known by the adapter including Connected
+  // Devices, GATT Connected Devices, Paired Devices and Devices discovered
+  // during a classic or low-energy scan.
+  GetDevices() => (array<DeviceInfo> devices);
+
+  // Sets the client that listens for the adapter's events.
+  SetClient(AdapterClient client);
+};
+
+interface AdapterClient {
+  // Called the first time a device is discovered.
+  DeviceAdded(DeviceInfo device);
+
+  // Called after the device hasn't been seen for 3 minutes.
+  DeviceRemoved(DeviceInfo device);
+};