src/vs/workbench/api/browser/mainThreadWebviewManager.ts/MainThreadWebviewManager/constructor
class MainThreadWebviewManager:	constructor(
		context: IExtHostContext,
		@IInstantiationService instantiationService: IInstantiationService,
	) {
		super();

		const webviews = this._register(instantiationService.createInstance(MainThreadWebviews, context));
		context.set(extHostProtocol.MainContext.MainThreadWebviews, webviews);

		const webviewPanels = this._register(instantiationService.createInstance(MainThreadWebviewPanels, context, webviews));
		context.set(extHostProtocol.MainContext.MainThreadWebviewPanels, webviewPanels);

		const customEditors = this._register(instantiationService.createInstance(MainThreadCustomEditors, context, webviews, webviewPanels));
		context.set(extHostProtocol.MainContext.MainThreadCustomEditors, customEditors);

		const webviewViews = this._register(instantiationService.createInstance(MainThreadWebviewsViews, context, webviews));
		context.set(extHostProtocol.MainContext.MainThreadWebviewViews, webviewViews);
	}