src/vs/workbench/api/common/extHostComments.ts/ExtHostComments/createCommentController
class ExtHostComments:	createCommentController(extension: IExtensionDescription, id: string, label: string): vscode.CommentController {
		const handle = ExtHostComments.handlePool++;
		const commentController = new ExtHostCommentController(extension, handle, this._proxy, id, label);
		this._commentControllers.set(commentController.handle, commentController);

		const commentControllers = this._commentControllersByExtension.get(ExtensionIdentifier.toKey(extension.identifier)) || [];
		commentControllers.push(commentController);
		this._commentControllersByExtension.set(ExtensionIdentifier.toKey(extension.identifier), commentControllers);

		return commentController;
	}