add theming API

src/vs/workbench/api/common/extHostTheming.ts

@@ -0,0 +1,38 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { ColorTheme, ColorThemeKind } from './extHostTypes';
+import { IExtHostRpcService } from 'vs/workbench/api/common/extHostRpcService';
+import { ExtHostThemingShape } from 'vs/workbench/api/common/extHost.protocol';
+import { Emitter, Event } from 'vs/base/common/event';
+
+export class ExtHostTheming implements ExtHostThemingShape {
+
+	readonly _serviceBrand: undefined;
+
+	private _actual: ColorTheme;
+	private _onDidChangeActiveColorTheme: Emitter<ColorTheme>;
+
+	constructor(
+		@IExtHostRpcService _extHostRpc: IExtHostRpcService
+	) {
+		this._actual = new ColorTheme(ColorThemeKind.Dark);
+		this._onDidChangeActiveColorTheme = new Emitter<ColorTheme>();
+	}
+
+	public get activeColorTheme(): ColorTheme {
+		return this._actual;
+	}
+
+	$onColorThemeChange(type: string): void {
+		let kind = type === 'light' ? ColorThemeKind.Light : type === 'dark' ? ColorThemeKind.Dark : ColorThemeKind.HighContrast;
+		this._actual = new ColorTheme(kind);
+		this._onDidChangeActiveColorTheme.fire(this._actual);
+	}
+
+	public get onDidChangeActiveColorTheme(): Event<ColorTheme> {
+		return this._onDidChangeActiveColorTheme.event;
+	}
+}