[TabManager] Move TabManager into chrome/browser/resource_coordinator.

chrome/browser/memory/tab_manager.h

Index: chrome/browser/memory/tab_manager.h
diff --git a/chrome/browser/memory/tab_manager.h b/chrome/browser/memory/tab_manager.h
deleted file mode 100644
index 23c5c5fb3bf681e048440775f657da77e83efcea..0000000000000000000000000000000000000000
--- a/chrome/browser/memory/tab_manager.h
+++ /dev/null
@@ -1,376 +0,0 @@
-// Copyright (c) 2012 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_MEMORY_TAB_MANAGER_H_
-#define CHROME_BROWSER_MEMORY_TAB_MANAGER_H_
-
-#include <stdint.h>
-
-#include <memory>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/compiler_specific.h"
-#include "base/gtest_prod_util.h"
-#include "base/macros.h"
-#include "base/memory/memory_pressure_listener.h"
-#include "base/memory/weak_ptr.h"
-#include "base/observer_list.h"
-#include "base/strings/string16.h"
-#include "base/timer/timer.h"
-#include "build/build_config.h"
-#include "chrome/browser/memory/tab_manager_observer.h"
-#include "chrome/browser/memory/tab_stats.h"
-#include "chrome/browser/ui/browser_tab_strip_tracker.h"
-#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
-
-class BrowserList;
-class GURL;
-class TabStripModel;
-
-namespace base {
-class TickClock;
-}
-
-namespace content {
-class WebContents;
-}
-
-namespace memory {
-
-#if defined(OS_CHROMEOS)
-class TabManagerDelegate;
-#endif
-
-// The TabManager periodically updates (see
-// |kAdjustmentIntervalSeconds| in the source) the status of renderers
-// which are then used by the algorithm embedded here for priority in being
-// killed upon OOM conditions.
-//
-// The algorithm used favors killing tabs that are not selected, not pinned,
-// and have been idle for longest, in that order of priority.
-//
-// On Chrome OS (via the delegate), the kernel (via /proc/<pid>/oom_score_adj)
-// will be informed of each renderer's score, which is based on the status, so
-// in case Chrome is not able to relieve the pressure quickly enough and the
-// kernel is forced to kill processes, it will be able to do so using the same
-// algorithm as the one used here.
-//
-// Note that the browser tests are only active for platforms that use
-// TabManager (CrOS only for now) and need to be adjusted accordingly if
-// support for new platforms is added.
-class TabManager : public TabStripModelObserver {
- public:
-  // Needs to be public for DEFINE_WEB_CONTENTS_USER_DATA_KEY.
-  class WebContentsData;
-
-  TabManager();
-  ~TabManager() override;
-
-  // Number of discard events since Chrome started.
-  int discard_count() const { return discard_count_; }
-
-  // See member comment.
-  bool recent_tab_discard() const { return recent_tab_discard_; }
-
-  // Start/Stop the Tab Manager.
-  void Start();
-  void Stop();
-
-  // Returns the list of the stats for all renderers. Must be called on the UI
-  // thread. The returned list is sorted by reversed importance.
-  TabStatsList GetTabStats() const;
-
-  // Returns true if |contents| is currently discarded.
-  bool IsTabDiscarded(content::WebContents* contents) const;
-
-  // Goes through a list of checks to see if a tab is allowed to be discarded by
-  // the automatic tab discarding mechanism. Note that this is not used when
-  // discarding a particular tab from about:discards.
-  bool CanDiscardTab(int64_t target_web_contents_id) const;
-
-  // Discards a tab to free the memory occupied by its renderer. The tab still
-  // exists in the tab-strip; clicking on it will reload it.
-  void DiscardTab();
-
-  // Discards a tab with the given unique ID. The tab still exists in the
-  // tab-strip; clicking on it will reload it. Returns null if the tab cannot
-  // be found or cannot be discarded. Otherwise returns the new web_contents
-  // of the discarded tab.
-  content::WebContents* DiscardTabById(int64_t target_web_contents_id);
-
-  // Method used by the extensions API to discard tabs. If |contents| is null,
-  // discards the least important tab using DiscardTab(). Otherwise discards
-  // the given contents. Returns the new web_contents or null if no tab
-  // was discarded.
-  content::WebContents* DiscardTabByExtension(content::WebContents* contents);
-
-  // Log memory statistics for the running processes, then discards a tab.
-  // Tab discard happens sometime later, as collecting the statistics touches
-  // multiple threads and takes time.
-  void LogMemoryAndDiscardTab();
-
-  // Log memory statistics for the running processes, then call the callback.
-  void LogMemory(const std::string& title, const base::Closure& callback);
-
-  // Used to set the test TickClock, which then gets used by NowTicks(). See
-  // |test_tick_clock_| for more details.
-  void set_test_tick_clock(base::TickClock* test_tick_clock);
-
-  // Returns the list of the stats for all renderers. Must be called on the UI
-  // thread.
-  TabStatsList GetUnsortedTabStats() const;
-
-  void AddObserver(TabManagerObserver* observer);
-  void RemoveObserver(TabManagerObserver* observer);
-
-  // Used in tests to change the protection time of the tabs.
-  void set_minimum_protection_time_for_tests(
-      base::TimeDelta minimum_protection_time);
-
-  // Returns the auto-discardable state of the tab. When true, the tab is
-  // eligible to be automatically discarded when critical memory pressure hits,
-  // otherwise the tab is ignored and will never be automatically discarded.
-  // Note that this property doesn't block the discarding of the tab via other
-  // methods (about:discards for instance).
-  bool IsTabAutoDiscardable(content::WebContents* contents) const;
-
-  // Sets/clears the auto-discardable state of the tab.
-  void SetTabAutoDiscardableState(content::WebContents* contents, bool state);
-
-  // Returns true when a given renderer can be purged if the specified
-  // renderer is eligible for purging.
-  // TODO(tasak): rename this to CanPurgeBackgroundedRenderer.
-  bool CanSuspendBackgroundedRenderer(int render_process_id) const;
-
-  // Returns true if |first| is considered less desirable to be killed than
-  // |second|.
-  static bool CompareTabStats(const TabStats& first, const TabStats& second);
-
-  // Returns a unique ID for a WebContents. Do not cast back to a pointer, as
-  // the WebContents could be deleted if the user closed the tab.
-  static int64_t IdFromWebContents(content::WebContents* web_contents);
-
- private:
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, PurgeBackgroundRenderer);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ActivateTabResetPurgeState);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ShouldPurgeAtDefaultTime);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DefaultTimeToPurgeInCorrectRange);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, AutoDiscardable);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, CanOnlyDiscardOnce);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ChildProcessNotifications);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, Comparator);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DiscardedTabKeepsLastActiveTime);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DiscardWebContentsAt);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, InvalidOrEmptyURL);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, IsInternalPage);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, OomPressureListener);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectPDFPages);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectRecentlyUsedTabs);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectVideoTabs);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ReloadDiscardedTabContextMenu);
-  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, TabManagerBasics);
-
-  // The time of the first purging after a renderer is backgrounded.
-  // The initial value was chosen because most of users activate backgrounded
-  // tabs within 30 minutes. (c.f. Tabs.StateTransfer.Time_Inactive_Active)
-  static constexpr base::TimeDelta kDefaultMinTimeToPurge =
-      base::TimeDelta::FromMinutes(30);
-
-  // The min/max time to purge ratio. The max time to purge is set to be
-  // min time to purge times this value.
-  const int kMinMaxTimeToPurgeRatio = 2;
-
-  // This is needed so WebContentsData can call OnDiscardedStateChange, and
-  // can use PurgeState.
-  friend class WebContentsData;
-
-  // Finds TabStripModel which has a WebContents whose id is the given
-  // web_contents_id, and returns the WebContents index and the TabStripModel.
-  int FindTabStripModelById(int64_t target_web_contents_id,
-                            TabStripModel** model) const;
-
-  // Called by WebContentsData whenever the discard state of a WebContents
-  // changes, so that observers can be informed.
-  void OnDiscardedStateChange(content::WebContents* contents,
-                              bool is_discarded);
-
-  // Called by WebContentsData whenever the auto-discardable state of a
-  // WebContents changes, so that observers can be informed.
-  void OnAutoDiscardableStateChange(content::WebContents* contents,
-                                    bool is_auto_discardable);
-
-  static void PurgeMemoryAndDiscardTab();
-
-  // Returns true if the |url| represents an internal Chrome web UI page that
-  // can be easily reloaded and hence makes a good choice to discard.
-  static bool IsInternalPage(const GURL& url);
-
-  // Records UMA histogram statistics for a tab discard. Record statistics for
-  // user triggered discards via chrome://discards/ because that allows to
-  // manually test the system.
-  void RecordDiscardStatistics();
-
-  // Record whether an out of memory occured during a recent time interval. This
-  // allows the normalization of low memory statistics versus usage.
-  void RecordRecentTabDiscard();
-
-  // Purges data structures in the browser that can be easily recomputed.
-  void PurgeBrowserMemory();
-
-  // Returns the number of tabs open in all browser instances.
-  int GetTabCount() const;
-
-  // Adds all the stats of the tabs to |stats_list|.
-  void AddTabStats(TabStatsList* stats_list) const;
-
-  // Adds all the stats of the tabs in |tab_strip_model| into |stats_list|.
-  // If |active_model| is true, consider its first tab as being active.
-  void AddTabStats(const TabStripModel* model,
-                   bool is_app,
-                   bool active_model,
-                   TabStatsList* stats_list) const;
-
-  // Callback for when |update_timer_| fires. Takes care of executing the tasks
-  // that need to be run periodically (see comment in implementation).
-  void UpdateTimerCallback();
-
-  // Returns WebContents whose contents id matches the given tab_contents_id.
-  content::WebContents* GetWebContentsById(int64_t tab_contents_id) const;
-
-  // Returns a random time-to-purge whose min value is min_time_to_purge and max
-  // value is min_time_to_purge * kMinMaxTimeToPurgeRatio.
-  base::TimeDelta GetTimeToPurge(base::TimeDelta min_time_to_purge) const;
-
-  // Returns true if the tab specified by |content| is now eligible to have
-  // its memory purged.
-  bool ShouldPurgeNow(content::WebContents* content) const;
-
-  // Purges renderers in backgrounded tabs if the following conditions are
-  // satisfied:
-  // - the renderers are not purged yet,
-  // - the renderers are not playing media,
-  //   (CanPurgeBackgroundedRenderer returns true)
-  // - the renderers are left inactive and background for time-to-purge.
-  // If renderers are purged, their internal states become 'purged'.
-  // The state is reset to be 'not purged' only when they are activated
-  // (=ActiveTabChanged is invoked).
-  void PurgeBackgroundedTabsIfNeeded();
-
-  // Does the actual discard by destroying the WebContents in |model| at |index|
-  // and replacing it by an empty one. Returns the new WebContents or NULL if
-  // the operation fails (return value used only in testing).
-  content::WebContents* DiscardWebContentsAt(int index, TabStripModel* model);
-
-  // Called by the memory pressure listener when the memory pressure rises.
-  void OnMemoryPressure(
-      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
-
-  // TabStripModelObserver overrides.
-  void TabChangedAt(content::WebContents* contents,
-                    int index,
-                    TabChangeType change_type) override;
-  void ActiveTabChanged(content::WebContents* old_contents,
-                        content::WebContents* new_contents,
-                        int index,
-                        int reason) override;
-  void TabInsertedAt(TabStripModel* tab_strip_model,
-                     content::WebContents* contents,
-                     int index,
-                     bool foreground) override;
-
-  // Returns true if the tab is currently playing audio or has played audio
-  // recently, or if the tab is currently accessing the camera, microphone or
-  // mirroring the display.
-  bool IsMediaTab(content::WebContents* contents) const;
-
-  // Returns the WebContentsData associated with |contents|. Also takes care of
-  // creating one if needed.
-  WebContentsData* GetWebContentsData(content::WebContents* contents) const;
-
-  // Returns either the system's clock or the test clock. See |test_tick_clock_|
-  // for more details.
-  base::TimeTicks NowTicks() const;
-
-  // Implementation of DiscardTab. Returns null if no tab was discarded.
-  // Otherwise returns the new web_contents of the discarded tab.
-  content::WebContents* DiscardTabImpl();
-
-  // Returns true if tabs can be discarded only once.
-  bool CanOnlyDiscardOnce() const;
-
-  // Timer to periodically update the stats of the renderers.
-  base::RepeatingTimer update_timer_;
-
-  // Timer to periodically report whether a tab has been discarded since the
-  // last time the timer has fired.
-  base::RepeatingTimer recent_tab_discard_timer_;
-
-  // A listener to global memory pressure events.
-  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
-
-  // Wall-clock time when the priority manager started running.
-  base::TimeTicks start_time_;
-
-  // Wall-clock time of last tab discard during this browsing session, or 0 if
-  // no discard has happened yet.
-  base::TimeTicks last_discard_time_;
-
-  // Wall-clock time of last priority adjustment, used to correct the above
-  // times for discontinuities caused by suspend/resume.
-  base::TimeTicks last_adjust_time_;
-
-  // Number of times a tab has been discarded, for statistics.
-  int discard_count_;
-
-  // Whether a tab discard event has occurred during the last time interval,
-  // used for statistics normalized by usage.
-  bool recent_tab_discard_;
-
-  // Whether a tab can only ever discarded once.
-  bool discard_once_;
-
-  // This allows protecting tabs for a certain amount of time after being
-  // backgrounded.
-  base::TimeDelta minimum_protection_time_;
-
-  // A backgrounded renderer will be purged when this time passes.
-  base::TimeDelta min_time_to_purge_;
-
-#if defined(OS_CHROMEOS)
-  std::unique_ptr<TabManagerDelegate> delegate_;
-#endif
-
-  // Responsible for automatically registering this class as an observer of all
-  // TabStripModels. Automatically tracks browsers as they come and go.
-  BrowserTabStripTracker browser_tab_strip_tracker_;
-
-  // Pointer to a test clock. If this is set, NowTicks() returns the value of
-  // this test clock. Otherwise it returns the system clock's value.
-  base::TickClock* test_tick_clock_;
-
-  // Injected tab strip models. Allows this to be tested end-to-end without
-  // requiring a full browser environment. If specified these tab strips will be
-  // crawled as the authoritative source of tabs, otherwise the BrowserList and
-  // associated Browser objects are crawled. The first of these is considered to
-  // be the 'active' tab strip model.
-  // TODO(chrisha): Factor out tab-strip model enumeration to a helper class,
-  //     and make a delegate that centralizes all testing seams.
-  using TestTabStripModel = std::pair<const TabStripModel*, bool>;
-  std::vector<TestTabStripModel> test_tab_strip_models_;
-
-  // List of observers that will receive notifications on state changes.
-  base::ObserverList<TabManagerObserver> observers_;
-
-  // Weak pointer factory used for posting delayed tasks.
-  base::WeakPtrFactory<TabManager> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(TabManager);
-};
-
-}  // namespace memory
-
-#endif  // CHROME_BROWSER_MEMORY_TAB_MANAGER_H_