chrome/browser/sessions/tab_loader.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   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_SESSIONS_TAB_LOADER_H_
   6 #define CHROME_BROWSER_SESSIONS_TAB_LOADER_H_
   7
   8 #include <list>
   9 #include <set>
  10
  11 #include "base/memory/memory_pressure_listener.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/timer/timer.h"
  14 #include "chrome/browser/sessions/session_restore_delegate.h"
  15 #include "chrome/browser/sessions/tab_loader_delegate.h"
  16 #include "content/public/browser/notification_observer.h"
  17 #include "content/public/browser/notification_registrar.h"
  18
  19 namespace content {
  20 class NavigationController;
  21 class RenderWidgetHost;
  22 }
  23
  24 class SessionRestoreStatsCollector;
  25
  26 // TabLoader is responsible for loading tabs after session restore has finished
  27 // creating all the tabs. Tabs are loaded after a previously tab finishes
  28 // loading or a timeout is reached. If the timeout is reached before a tab
  29 // finishes loading the timeout delay is doubled.
  30 //
  31 // TabLoader keeps a reference to itself when it's loading. When it has finished
  32 // loading, it drops the reference. If another profile is restored while the
  33 // TabLoader is loading, it will schedule its tabs to get loaded by the same
  34 // TabLoader. When doing the scheduling, it holds a reference to the TabLoader.
  35 //
  36 // This is not part of SessionRestoreImpl so that synchronous destruction
  37 // of SessionRestoreImpl doesn't have timing problems.
  38 class TabLoader : public content::NotificationObserver,
  39                   public base::RefCounted<TabLoader>,
  40                   public TabLoaderCallback {
  41  public:
  42   using RestoredTab = SessionRestoreDelegate::RestoredTab;
  43
  44   // NotificationObserver method. Removes the specified tab and loads the next
  45   // tab.
  46   void Observe(int type,
  47                const content::NotificationSource& source,
  48                const content::NotificationDetails& details) override;
  49
  50   // TabLoaderCallback:
  51   void SetTabLoadingEnabled(bool enable_tab_loading) override;
  52
  53   // Called to start restoring tabs.
  54   static void RestoreTabs(const std::vector<RestoredTab>& tabs_,
  55                           const base::TimeTicks& restore_started);
  56
  57  private:
  58   friend class base::RefCounted<TabLoader>;
  59
  60   using TabsLoading = std::set<content::NavigationController*>;
  61   using TabsToLoad = std::list<content::NavigationController*>;
  62
  63   explicit TabLoader(base::TimeTicks restore_started);
  64   ~TabLoader() override;
  65
  66   // This is invoked once by RestoreTabs to start loading.
  67   void StartLoading(const std::vector<RestoredTab>& tabs);
  68
  69   // Loads the next tab. If there are no more tabs to load this deletes itself,
  70   // otherwise |force_load_timer_| is restarted.
  71   void LoadNextTab();
  72
  73   // Starts |force_load_timer_| to load the first non-visible tab if the timer
  74   // expires before a visible tab has finished loading. This uses the same
  75   // timer but a different timeout value than StartTimer.
  76   void StartFirstTimer();
  77
  78   // Starts |force_load_timer_| to load the next tab if the timer expires
  79   // before the current tab loading is finished. This uses the same timer but a
  80   // different timeout value than StartFirstTimer.
  81   void StartTimer();
  82
  83   // Removes the listeners from the specified tab and removes the tab from
  84   // the set of tabs to load and list of tabs we're waiting to get a load
  85   // from.
  86   void RemoveTab(content::NavigationController* controller);
  87
  88   // Invoked from |force_load_timer_|. Doubles |force_load_delay_multiplier_|
  89   // and invokes |LoadNextTab| to load the next tab
  90   void ForceLoadTimerFired();
  91
  92   // Returns the RenderWidgetHost associated with a tab if there is one,
  93   // NULL otherwise.
  94   static content::RenderWidgetHost* GetRenderWidgetHost(
  95       content::NavigationController* controller);
  96
  97   // Register for necessary notifications on a tab navigation controller.
  98   void RegisterForNotifications(content::NavigationController* controller);
  99
 100   // Called when a tab goes away or a load completes.
 101   void HandleTabClosedOrLoaded(content::NavigationController* controller);
 102
 103   // React to memory pressure by stopping to load any more tabs.
 104   void OnMemoryPressure(
 105       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 106
 107   scoped_ptr<TabLoaderDelegate> delegate_;
 108
 109   // Listens for system under memory pressure notifications and stops loading
 110   // of tabs when we start running out of memory.
 111   base::MemoryPressureListener memory_pressure_listener_;
 112
 113   content::NotificationRegistrar registrar_;
 114
 115   // The delay timer multiplier. See class description for details.
 116   size_t force_load_delay_multiplier_;
 117
 118   // True if the tab loading is enabled.
 119   bool loading_enabled_;
 120
 121   // The set of tabs we've initiated loading on. This does NOT include the
 122   // selected tabs.
 123   TabsLoading tabs_loading_;
 124
 125   // The tabs we need to load.
 126   TabsToLoad tabs_to_load_;
 127
 128   base::OneShotTimer<TabLoader> force_load_timer_;
 129
 130   // The time the restore process started.
 131   base::TimeTicks restore_started_;
 132
 133   // For keeping TabLoader alive while it's loading even if no
 134   // SessionRestoreImpls reference it.
 135   scoped_refptr<TabLoader> this_retainer_;
 136
 137   // The SessionRestoreStatsCollector associated with this TabLoader. This is
 138   // explicitly referenced so that it can be notified of deferred tab loads due
 139   // to memory pressure.
 140   scoped_refptr<SessionRestoreStatsCollector> stats_collector_;
 141
 142   static TabLoader* shared_tab_loader_;
 143
 144   DISALLOW_COPY_AND_ASSIGN(TabLoader);
 145 };
 146
 147 #endif  // CHROME_BROWSER_SESSIONS_TAB_LOADER_H_