vscode-extension-samples/theme-sample/package.json

{
	"name": "theme-sample",
	"version": "0.1.0",
	"publisher": "vscode",
	"engines": {
		"vscode": "*"
	},
	"contributes": {
		"themes": [
			{
				"label": "Sample Light",
				"uiTheme": "vs",
				"path": "./Sample_Light.tmTheme"
			},
			{
				"label": "Sample Dark",
				"uiTheme": "vs-dark",
				"path": "./Sample_Dark.tmTheme"
			}
		]
	}
}