fix(toolbox) add back toggle camera button

react/features/base/config/constants.js

     'fodeviceselection', 'hangup', 'profile', 'chat', 'recording',
     'livestreaming', 'etherpad', 'sharedvideo', 'shareaudio', 'settings', 'raisehand',
     'videoquality', 'filmstrip', 'participants-pane', 'feedback', 'stats', 'shortcuts',
-    'tileview', 'select-background', 'download', 'help', 'mute-everyone', 'mute-video-everyone',
+    'tileview', 'toggle-camera', 'select-background', 'download', 'help', 'mute-everyone', 'mute-video-everyone',
     'security'
 ];

react/features/toolbox/components/web/ToggleCameraButton.js

+// @flow
+
+import { translate } from '../../../base/i18n';
+import { IconCameraRefresh } from '../../../base/icons';
+import { connect } from '../../../base/redux';
+import { AbstractButton, type AbstractButtonProps } from '../../../base/toolbox/components';
+import { isLocalCameraTrackMuted, isToggleCameraEnabled, toggleCamera } from '../../../base/tracks';
+
+/**
+ * The type of the React {@code Component} props of {@link ToggleCameraButton}.
+ */
+type Props = AbstractButtonProps & {
+
+    /**
+     * Whether the current conference is in audio only mode or not.
+     */
+    _audioOnly: boolean,
+
+    /**
+     * Whether video is currently muted or not.
+     */
+    _videoMuted: boolean,
+
+    /**
+     * The Redux dispatch function.
+     */
+    dispatch: Function
+};
+
+/**
+ * An implementation of a button for toggling the camera facing mode.
+ */
+class ToggleCameraButton extends AbstractButton<Props, any> {
+    accessibilityLabel = 'toolbar.accessibilityLabel.toggleCamera';
+    icon = IconCameraRefresh;
+    label = 'toolbar.toggleCamera';
+
+    /**
+     * Handles clicking/pressing the button.
+     *
+     * @returns {void}
+     */
+    _handleClick() {
+        this.props.dispatch(toggleCamera());
+    }
+
+    /**
+     * Whether this button is disabled or not.
+     *
+     * @returns {boolean}
+     */
+    _isDisabled() {
+        return this.props._audioOnly || this.props._videoMuted;
+    }
+}
+
+/**
+ * Maps (parts of) the redux state to the associated props for the
+ * {@code ToggleCameraButton} component.
+ *
+ * @param {Object} state - The Redux state.
+ * @returns {Props}
+ */
+function mapStateToProps(state): Object {
+    const { enabled: audioOnly } = state['features/base/audio-only'];
+    const tracks = state['features/base/tracks'];
+
+    return {
+        _audioOnly: Boolean(audioOnly),
+        _videoMuted: isLocalCameraTrackMuted(tracks),
+        visible: isToggleCameraEnabled(state)
+    };
+}
+
+export default translate(connect(mapStateToProps)(ToggleCameraButton));

react/features/toolbox/components/web/Toolbox.js

 import RaiseHandButton from './RaiseHandButton';
 import Separator from './Separator';
 import ShareDesktopButton from './ShareDesktopButton';
+import ToggleCameraButton from './ToggleCameraButton';
 import VideoSettingsButton from './VideoSettingsButton';
 
 /**
             group: 2
         };
 
+        const toggleCamera = {
+            key: 'toggle-camera',
+            Content: ToggleCameraButton,
+            group: 2
+        };
+
         const videoQuality = {
             key: 'videoquality',
             Content: VideoQualityButton,
             raisehand,
             participants,
             tileview,
+            toggleCamera,
             videoQuality,
             fullscreen,
             security,