chrome/browser/visibility_timer_tab_helper.h

   1 // Copyright 2020 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_
   6 #define CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_
   7
   8 #include "base/containers/circular_deque.h"
   9 #include "base/functional/callback_forward.h"
  10 #include "base/timer/timer.h"
  11 #include "content/public/browser/web_contents_observer.h"
  12 #include "content/public/browser/web_contents_user_data.h"
  13
  14 // At most one of these is attached to each WebContents. It allows posting
  15 // delayed tasks whose timer only counts down whilst the WebContents is visible
  16 // (and whose timer is reset whenever the WebContents stops being visible).
  17 // If multiple tasks are added, they are queued in a dormant state -- their
  18 // timer will not elapse until earlier tasks are completed.
  19 class VisibilityTimerTabHelper
  20     : public content::WebContentsObserver,
  21       public content::WebContentsUserData<VisibilityTimerTabHelper> {
  22  public:
  23   VisibilityTimerTabHelper(const VisibilityTimerTabHelper&&) = delete;
  24   VisibilityTimerTabHelper& operator=(const VisibilityTimerTabHelper&&) =
  25       delete;
  26
  27   ~VisibilityTimerTabHelper() override;
  28
  29   // Runs |task| after the WebContents has been visible for a consecutive
  30   // duration of at least |visible_delay|.
  31   void PostTaskAfterVisibleDelay(const base::Location& from_here,
  32                                  base::OnceClosure task,
  33                                  base::TimeDelta visible_delay);
  34
  35   // WebContentsObserver:
  36   void OnVisibilityChanged(content::Visibility visibility) override;
  37
  38  private:
  39   struct Task;
  40   friend class content::WebContentsUserData<VisibilityTimerTabHelper>;
  41   explicit VisibilityTimerTabHelper(content::WebContents* contents);
  42
  43   void RunTask(base::OnceClosure task);
  44   void StartNextTaskTimer();
  45
  46   base::OneShotTimer timer_;
  47   base::circular_deque<Task> task_queue_;
  48
  49   WEB_CONTENTS_USER_DATA_KEY_DECL();
  50 };
  51
  52 #endif  // CHROME_BROWSER_VISIBILITY_TIMER_TAB_HELPER_H_