feat(SS): pass the source type to lib-jitsi-meet.

conference.js

      */
     getDesktopSharingSourceId() {
         return localVideo.sourceId;
+    },
+
+    /**
+     * Returns the desktop sharing source type or undefined if the desktop
+     * sharing is not active at the moment.
+     *
+     * @returns {'screen'|'window'|undefined} - The source type. If the track is
+     * not desktop track or the source type is not available, undefined will be
+     * returned.
+     */
+    getDesktopSharingSourceType() {
+        return localVideo.sourceType;
     }
 };

react/features/desktop-picker/components/DesktopPicker.js

         super(props);
 
         this.state = {
-            selectedSourceId: ''
+            selectedSource: {}
         };
 
         this._poller = null;
      * @returns {void}
      */
     componentWillReceiveProps(nextProps) {
-        if (!this.state.selectedSourceId
+        if (!this.state.selectedSource.id
                 && nextProps.sources.screen.length) {
             this.setState({
-                selectedSourceId: nextProps.sources.screen[0].id
+                selectedSource: {
+                    id: nextProps.sources.screen[0].id,
+                    type: 'screen'
+                }
             });
         }
     }
 
     /**
      * Dispatches an action to hide the DesktopPicker and invokes the passed in
-     * callback with a selectedSourceId, if any.
+     * callback with a selectedSource, if any.
      *
      * @param {string} id - The id of the DesktopCapturerSource to pass into the
      * onSourceChoose callback.
+     * @param {string} type - The type of the DesktopCapturerSource to pass into
+     * the onSourceChoose callback.
      * @returns {void}
      */
-    _onCloseModal(id = '') {
-        this.props.onSourceChoose(id);
+    _onCloseModal(id, type) {
+        this.props.onSourceChoose(id, type);
         this.props.dispatch(hideDialog());
     }
 
      * Sets the currently selected DesktopCapturerSource.
      *
      * @param {string} id - The id of DesktopCapturerSource.
+     * @param {string} type - The type of DesktopCapturerSource.
      * @returns {void}
      */
-    _onPreviewClick(id) {
-        this.setState({ selectedSourceId: id });
+    _onPreviewClick(id, type) {
+        this.setState({
+            selectedSource: {
+                id,
+                type
+            }
+        });
     }
 
     /**
      * @returns {void}
      */
     _onSubmit() {
-        this._onCloseModal(this.state.selectedSourceId);
+        const { id, type } = this.state.selectedSource;
+
+        this._onCloseModal(id, type);
     }
 
     /**
      * @returns {ReactElement}
      */
     _renderTabs() {
-        const { selectedSourceId } = this.state;
+        const { selectedSource } = this.state;
         const { sources, t } = this.props;
         const tabs
             = TABS_TO_POPULATE.map(({ defaultSelected, label, type }) => {
                         key = { type }
                         onClick = { this._onPreviewClick }
                         onDoubleClick = { this._onCloseModal }
-                        selectedSourceId = { selectedSourceId }
+                        selectedSourceId = { selectedSource.id }
                         sources = { sources[type] || [] }
                         type = { type } />,
                     defaultSelected,

react/features/desktop-picker/components/DesktopPickerPane.js

                         onClick = { onClick }
                         onDoubleClick = { onDoubleClick }
                         selected = { source.id === selectedSourceId }
-                        source = { source } />);
+                        source = { source }
+                        type = { type } />);
 
         return (
             <div className = { classNames }>

react/features/desktop-picker/components/DesktopSourcePreview.js

         /**
          * The DesktopCapturerSource to display.
          */
-        source: React.PropTypes.object
+        source: React.PropTypes.object,
+
+        /**
+         * The source type of the DesktopCapturerSources to display.
+         */
+        type: React.PropTypes.string
     };
 
     /**
      * @returns {void}
      */
     _onClick() {
-        this.props.onClick(this.props.source.id);
+        const { source, type } = this.props;
+
+        this.props.onClick(source.id, type);
     }
 
     /**
      * @returns {void}
      */
     _onDoubleClick() {
-        this.props.onDoubleClick(this.props.source.id);
+        const { source, type } = this.props;
+
+        this.props.onDoubleClick(source.id, type);
     }
 }