/**
 * @license
 * Copyright 2020 Google Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
/**
 * AnimationFrame provides a user-friendly abstraction around requesting
 * and canceling animation frames.
 */
export declare class AnimationFrame {
    private readonly rafIDs;
    /**
     * Requests an animation frame. Cancels any existing frame with the same key.
     * @param {string} key The key for this callback.
     * @param {FrameRequestCallback} callback The callback to be executed.
     */
    request(key: string, callback: FrameRequestCallback): void;
    /**
     * Cancels a queued callback with the given key.
     * @param {string} key The key for this callback.
     */
    cancel(key: string): void;
    /**
     * Cancels all queued callback.
     */
    cancelAll(): void;
    /**
     * Returns the queue of unexecuted callback keys.
     */
    getQueue(): string[];
}