chromium/chrome/browser/visibility_timer_tab_helper.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_
#define CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_

#include "base/containers/circular_deque.h"
#include "base/functional/callback_forward.h"
#include "base/timer/timer.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/browser/web_contents_user_data.h"

// At most one of these is attached to each WebContents. It allows posting
// delayed tasks whose timer only counts down whilst the WebContents is visible
// (and whose timer is reset whenever the WebContents stops being visible).
// If multiple tasks are added, they are queued in a dormant state -- their
// timer will not elapse until earlier tasks are completed.
class VisibilityTimerTabHelper
    : public content::WebContentsObserver,
      public content::WebContentsUserData<VisibilityTimerTabHelper> { … };

#endif  // CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_