VSCode merge (#4610)

* Merge from vscode e388c734f30757875976c7e326d6cfeee77710de

* fix yarn lcoks

* remove small issue

src/vs/workbench/services/extensions/common/proxyIdentifier.ts

@@ -0,0 +1,55 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+export interface IRPCProtocol {
+	/**
+	 * Returns a proxy to an object addressable/named in the extension host process or in the renderer process.
+	 */
+	getProxy<T>(identifier: ProxyIdentifier<T>): T;
+
+	/**
+	 * Register manually created instance.
+	 */
+	set<T, R extends T>(identifier: ProxyIdentifier<T>, instance: R): R;
+
+	/**
+	 * Assert these identifiers are already registered via `.set`.
+	 */
+	assertRegistered(identifiers: ProxyIdentifier<any>[]): void;
+}
+
+export class ProxyIdentifier<T> {
+	public static count = 0;
+	_proxyIdentifierBrand: void;
+	_suppressCompilerUnusedWarning: T;
+
+	public readonly isMain: boolean;
+	public readonly sid: string;
+	public readonly nid: number;
+
+	constructor(isMain: boolean, sid: string) {
+		this.isMain = isMain;
+		this.sid = sid;
+		this.nid = (++ProxyIdentifier.count);
+	}
+}
+
+const identifiers: ProxyIdentifier<any>[] = [];
+
+export function createMainContextProxyIdentifier<T>(identifier: string): ProxyIdentifier<T> {
+	const result = new ProxyIdentifier<T>(true, identifier);
+	identifiers[result.nid] = result;
+	return result;
+}
+
+export function createExtHostContextProxyIdentifier<T>(identifier: string): ProxyIdentifier<T> {
+	const result = new ProxyIdentifier<T>(false, identifier);
+	identifiers[result.nid] = result;
+	return result;
+}
+
+export function getStringIdentifierForProxy(nid: number): string {
+	return identifiers[nid].sid;
+}