Add chrome.hid.getUserSelectedDevices API.

extensions/test/data/api_test/hid/get_user_selected_devices/background.js

+// Copyright 2015 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.
+
+var device_from_user;
+
+chrome.test.runWithUserGesture(function() {
+  chrome.hid.getDevices({}, function(devices) {
+    chrome.test.assertNoLastError();
+    chrome.test.assertEq(0, devices.length);
+    chrome.hid.getUserSelectedDevices({ multiple: false }, function(devices) {
+      chrome.test.assertNoLastError();
+      chrome.test.assertEq(1, devices.length);
+      device_from_user = devices[0];
+      chrome.hid.connect(device_from_user.deviceId, function(connection) {
+        chrome.test.assertNoLastError();
+        chrome.hid.disconnect(connection.connectionId);
+        chrome.test.sendMessage("opened_device");
+      });
+    });
+  });
+});
+
+chrome.hid.onDeviceRemoved.addListener(function(deviceId) {
+  chrome.test.assertEq(device_from_user.deviceId, deviceId);
+  chrome.test.sendMessage("removed");
+});
+
+chrome.hid.onDeviceAdded.addListener(function(device) {
+  chrome.test.assertTrue(device_from_user.deviceId != device.deviceId);
+  chrome.test.assertEq(device_from_user.vendorId, device.vendorId);
+  chrome.test.assertEq(device_from_user.productId, device.productId);
+  chrome.test.sendMessage("added");
+});