explorerDecorationProvider also react on added roots

src/vs/workbench/parts/files/electron-browser/views/explorerDecorationsProvider.ts

@@ -22,7 +22,7 @@ export class ExplorerDecorationsProvider implements IDecorationsProvider {
 		@IWorkspaceContextService contextService: IWorkspaceContextService
 	) {
 		contextService.onDidChangeWorkspaceFolders(e => {
-			this._onDidChange.fire(e.changed.map(wf => wf.uri));
+			this._onDidChange.fire(e.changed.concat(e.added).map(wf => wf.uri));
 		});
 	}