[MemoryPressure] Move chrome/browser/chromeos/* to chrome/browser/memory/*.

chrome/browser/chromeos/memory/oom_priority_manager.h

-// 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_CHROMEOS_MEMORY_OOM_PRIORITY_MANAGER_H_
-#define CHROME_BROWSER_CHROMEOS_MEMORY_OOM_PRIORITY_MANAGER_H_
-
-#include <utility>
-#include <vector>
-
-#include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
-#include "base/gtest_prod_util.h"
-#include "base/memory/memory_pressure_listener.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/process/process.h"
-#include "base/strings/string16.h"
-#include "base/synchronization/lock.h"
-#include "base/time/time.h"
-#include "base/timer/timer.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
-
-class GURL;
-
-namespace chromeos {
-
-class LowMemoryObserver;
-
-// The OomPriorityManager periodically checks (see
-// ADJUSTMENT_INTERVAL_SECONDS in the source) the status of renderers
-// and adjusts the out of memory (OOM) adjustment value (in
-// /proc/<pid>/oom_score_adj) of the renderers so that they match 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.
-class OomPriorityManager : public content::NotificationObserver {
- public:
-  OomPriorityManager();
-  ~OomPriorityManager() 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_; }
-
-  void Start();
-  void Stop();
-
-  // Returns list of tab titles sorted from most interesting (don't kill)
-  // to least interesting (OK to kill).
-  std::vector<base::string16> GetTabTitles();
-
-  // Discards a tab to free the memory occupied by its renderer.
-  // Tab still exists in the tab-strip; clicking on it will reload it.
-  // Returns true if it successfully found a tab and discarded it.
-  bool DiscardTab();
-
-  // 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);
-
- private:
-  FRIEND_TEST_ALL_PREFIXES(OomPriorityManagerTest, Comparator);
-  FRIEND_TEST_ALL_PREFIXES(OomPriorityManagerTest, IsReloadableUI);
-  FRIEND_TEST_ALL_PREFIXES(OomPriorityManagerTest, GetProcessHandles);
-
-  struct TabStats {
-    TabStats();
-    ~TabStats();
-    bool is_app;  // browser window is an app
-    bool is_reloadable_ui;  // Reloadable web UI page, like NTP or Settings.
-    bool is_playing_audio;
-    bool is_pinned;
-    bool is_selected;  // selected in the currently active browser window
-    bool is_discarded;
-    base::TimeTicks last_active;
-    base::ProcessHandle renderer_handle;
-    int child_process_host_id;
-    base::string16 title;
-    int64 tab_contents_id;  // unique ID per WebContents
-  };
-  typedef std::vector<TabStats> TabStatsList;
-
-  static void PurgeMemoryAndDiscardTabs();
-
-  // 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 IsReloadableUI(const GURL& url);
-
-  // Discards a tab with the given unique ID.  Returns true if discard occurred.
-  bool DiscardTabById(int64 target_web_contents_id);
-
-  // Records UMA histogram statistics for a tab discard. We record statistics
-  // for user triggered discards via chrome://discards/ because that allows us
-  // to manually test the system.
-  void RecordDiscardStatistics();
-
-  // Record whether we ran out of memory during a recent time interval.
-  // This allows us to normalize 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;
-
-  TabStatsList GetTabStatsOnUIThread();
-
-  // Called when the timer fires, sets oom_adjust_score for all renderers.
-  void AdjustOomPriorities();
-
-  // Pair to hold child process host id and ProcessHandle
-  typedef std::pair<int, base::ProcessHandle> ProcessInfo;
-
-  // Returns a list of child process host ids and ProcessHandles from
-  // |stats_list| with unique pids. If multiple tabs use the same process,
-  // returns the first child process host id and corresponding pid. This implies
-  // that the processes are selected based on their "most important" tab.
-  static std::vector<ProcessInfo> GetChildProcessInfos(
-      const TabStatsList& stats_list);
-
-  // Called by AdjustOomPriorities.
-  void AdjustOomPrioritiesOnFileThread(TabStatsList stats_list);
-
-  // Posts AdjustFocusedTabScore task to the file thread.
-  void OnFocusTabScoreAdjustmentTimeout();
-
-  // Sets the score of the focused tab to the least value.
-  void AdjustFocusedTabScoreOnFileThread();
-
-  static bool CompareTabStats(TabStats first, TabStats second);
-
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-
-  // Called by the memory pressure listener when the memory pressure rises.
-  void OnMemoryPressure(
-      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
-
-  base::RepeatingTimer<OomPriorityManager> timer_;
-  base::OneShotTimer<OomPriorityManager> focus_tab_score_adjust_timer_;
-  base::RepeatingTimer<OomPriorityManager> recent_tab_discard_timer_;
-  content::NotificationRegistrar registrar_;
-
-  // This lock is for |oom_score_map_| and |focused_tab_process_info_|.
-  base::Lock oom_score_lock_;
-  // Map maintaining the child process host id - oom_score mapping.
-  typedef base::hash_map<int, int> ProcessScoreMap;
-  ProcessScoreMap oom_score_map_;
-  // Holds the focused tab's child process host id.
-  ProcessInfo focused_tab_process_info_;
-
-  // The old observer for the kernel low memory signal. This is null if
-  // the new MemoryPressureListener is used.
-  // TODO(skuhne): Remove this when the enhanced memory observer is turned on
-  // by default.
-  scoped_ptr<LowMemoryObserver> low_memory_observer_;
-
-  // A listener to global memory pressure events. This will be used if the
-  // memory pressure system was instantiated - otherwise the LowMemoryObserver
-  // will be used.
-  scoped_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 we have discarded a tab, 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_;
-
-  DISALLOW_COPY_AND_ASSIGN(OomPriorityManager);
-};
-
-}  // namespace chromeos
-
-#endif  // CHROME_BROWSER_CHROMEOS_MEMORY_OOM_PRIORITY_MANAGER_H_