add theming API

src/vs/workbench/api/browser/mainThreadTheming.ts

@@ -0,0 +1,33 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { MainContext, IExtHostContext, ExtHostThemingShape, ExtHostContext, MainThreadThemingShape } from '../common/extHost.protocol';
+import { extHostNamedCustomer } from 'vs/workbench/api/common/extHostCustomers';
+import { IDisposable } from 'vs/base/common/lifecycle';
+import { IThemeService } from 'vs/platform/theme/common/themeService';
+
+@extHostNamedCustomer(MainContext.MainThreadTheming)
+export class MainThreadTheming implements MainThreadThemingShape {
+
+	private readonly _themeService: IThemeService;
+	private readonly _proxy: ExtHostThemingShape;
+	private readonly _themeChangeListener: IDisposable;
+
+	constructor(
+		extHostContext: IExtHostContext,
+		@IThemeService themeService: IThemeService
+	) {
+		this._themeService = themeService;
+		this._proxy = extHostContext.getProxy(ExtHostContext.ExtHostTheming);
+
+		this._themeChangeListener = this._themeService.onThemeChange(e => {
+			this._proxy.$onColorThemeChange(this._themeService.getTheme().type);
+		});
+	}
+
+	dispose(): void {
+		this._themeChangeListener.dispose();
+	}
+}