import type { IConfigCatCache } from "../ConfigCatCache.js";
interface ILocalStorage {
    set<T = {
        [key: string]: any;
    }>(items: Partial<T>): Promise<void>;
    get<T = {
        [key: string]: any;
    }>(keys: string): Promise<T>;
}
export declare class ChromeLocalStorageConfigCache implements IConfigCatCache {
    private readonly storage;
    private static tryGetFactory;
    constructor(storage: ILocalStorage);
    set(key: string, value: string): Promise<void>;
    get(key: string): Promise<string | undefined>;
}
export declare function getChromeLocalStorage(): ILocalStorage | undefined;
export declare function toUtf8Base64(str: string): string;
export declare function fromUtf8Base64(str: string): string;
export {};