Site Settings Desktop: Implement media picker for camera/mic categories.

chrome/browser/resources/settings/site_settings/media_picker.js

+// 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.
+
+/**
+ * @fileoverview
+ * 'media-picker' handles showing the dropdown allowing users to select the
+ * default camera/microphone.
+ */
+Polymer({
+  is: 'media-picker',
+
+  behaviors: [SiteSettingsBehavior, WebUIListenerBehavior],
+
+  properties: {
+    /**
+     * The type of media picker, either 'camera' or 'mic'.
+     */
+    type: String,
+
+    /**
+     * The devices available to pick from.
+     * @type {Array<MediaPickerEntry>}
+     */
+    devices: Array,
+  },
+
+  ready: function() {
+    this.addWebUIListener('updateDevicesMenu',
+        this.updateDevicesMenu_.bind(this));
+    this.browserProxy.getDefaultCaptureDevices(this.type);
+  },
+
+  /**
+   * Updates the microphone/camera devices menu with the given entries.
+   * @param {string} type The device type.
+   * @param {!Array<MediaPickerEntry>} devices List of available devices.
+   * @param {string} defaultDevice The unique id of the current default device.
+   */
+  updateDevicesMenu_: function(type, devices, defaultDevice) {
+    if (type != this.type)
+      return;
+
+    this.$.picker.hidden = devices.length == 0;
+    if (devices.length > 0) {
+      this.devices = devices;
+      this.$.mediaPicker.selected = defaultDevice;
+    }
+  },
+
+  /**
+   * A handler for when an item is selected in the media picker.
+   */
+  onMediaPickerActivate_: function(event) {
+    this.browserProxy.setDefaultCaptureDevice(this.type, event.detail.selected);
+  },
+});