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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_SESSIONS_TAB_LOADER_H_
#define CHROME_BROWSER_SESSIONS_TAB_LOADER_H_
#include <list>
#include <set>
#include "base/memory/memory_pressure_listener.h"
#include "base/memory/scoped_ptr.h"
#include "base/timer/timer.h"
#include "chrome/browser/sessions/session_restore_delegate.h"
#include "chrome/browser/sessions/tab_loader_delegate.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
namespace content {
class NavigationController;
class RenderWidgetHost;
}
class SessionRestoreStatsCollector;
// TabLoader is responsible for loading tabs after session restore has finished
// creating all the tabs. Tabs are loaded after a previously tab finishes
// loading or a timeout is reached. If the timeout is reached before a tab
// finishes loading the timeout delay is doubled.
//
// TabLoader keeps a reference to itself when it's loading. When it has finished
// loading, it drops the reference. If another profile is restored while the
// TabLoader is loading, it will schedule its tabs to get loaded by the same
// TabLoader. When doing the scheduling, it holds a reference to the TabLoader.
//
// This is not part of SessionRestoreImpl so that synchronous destruction
// of SessionRestoreImpl doesn't have timing problems.
class TabLoader : public content::NotificationObserver,
public base::RefCounted<TabLoader>,
public TabLoaderCallback {
public:
using RestoredTab = SessionRestoreDelegate::RestoredTab;
// NotificationObserver method. Removes the specified tab and loads the next
// tab.
void Observe(int type,
const content::NotificationSource& source,
const content::NotificationDetails& details) override;
// TabLoaderCallback:
void SetTabLoadingEnabled(bool enable_tab_loading) override;
// Called to start restoring tabs.
static void RestoreTabs(const std::vector<RestoredTab>& tabs_,
const base::TimeTicks& restore_started);
private:
friend class base::RefCounted<TabLoader>;
using TabsLoading = std::set<content::NavigationController*>;
using TabsToLoad = std::list<content::NavigationController*>;
explicit TabLoader(base::TimeTicks restore_started);
~TabLoader() override;
// This is invoked once by RestoreTabs to start loading.
void StartLoading(const std::vector<RestoredTab>& tabs);
// Loads the next tab. If there are no more tabs to load this deletes itself,
// otherwise |force_load_timer_| is restarted.
void LoadNextTab();
// Starts |force_load_timer_| to load the first non-visible tab if the timer
// expires before a visible tab has finished loading. This uses the same
// timer but a different timeout value than StartTimer.
void StartFirstTimer();
// Starts |force_load_timer_| to load the next tab if the timer expires
// before the current tab loading is finished. This uses the same timer but a
// different timeout value than StartFirstTimer.
void StartTimer();
// Removes the listeners from the specified tab and removes the tab from
// the set of tabs to load and list of tabs we're waiting to get a load
// from.
void RemoveTab(content::NavigationController* controller);
// Invoked from |force_load_timer_|. Doubles |force_load_delay_multiplier_|
// and invokes |LoadNextTab| to load the next tab
void ForceLoadTimerFired();
// Returns the RenderWidgetHost associated with a tab if there is one,
// NULL otherwise.
static content::RenderWidgetHost* GetRenderWidgetHost(
content::NavigationController* controller);
// Register for necessary notifications on a tab navigation controller.
void RegisterForNotifications(content::NavigationController* controller);
// Called when a tab goes away or a load completes.
void HandleTabClosedOrLoaded(content::NavigationController* controller);
// Convenience function returning the current memory pressure level.
base::MemoryPressureListener::MemoryPressureLevel
CurrentMemoryPressureLevel();
// React to memory pressure by stopping to load any more tabs.
void OnMemoryPressure(
base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
scoped_ptr<TabLoaderDelegate> delegate_;
// Listens for system under memory pressure notifications and stops loading
// of tabs when we start running out of memory.
base::MemoryPressureListener memory_pressure_listener_;
content::NotificationRegistrar registrar_;
// The delay timer multiplier. See class description for details.
size_t force_load_delay_multiplier_;
// True if the tab loading is enabled.
bool loading_enabled_;
// The set of tabs we've initiated loading on. This does NOT include the
// selected tabs.
TabsLoading tabs_loading_;
// The tabs we need to load.
TabsToLoad tabs_to_load_;
base::OneShotTimer force_load_timer_;
// The time the restore process started.
base::TimeTicks restore_started_;
// For keeping TabLoader alive while it's loading even if no
// SessionRestoreImpls reference it.
scoped_refptr<TabLoader> this_retainer_;
// The SessionRestoreStatsCollector associated with this TabLoader. This is
// explicitly referenced so that it can be notified of deferred tab loads due
// to memory pressure.
scoped_refptr<SessionRestoreStatsCollector> stats_collector_;
static TabLoader* shared_tab_loader_;
DISALLOW_COPY_AND_ASSIGN(TabLoader);
};
#endif // CHROME_BROWSER_SESSIONS_TAB_LOADER_H_