chrome/browser/sessions/session_service.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_SESSIONS_SESSION_SERVICE_H_
#define CHROME_BROWSER_SESSIONS_SESSION_SERVICE_H_

#include <map>
#include <string>

#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/optional.h"
#include "chrome/browser/sessions/session_service_base.h"
#include "chrome/browser/ui/browser.h"
#include "components/sessions/core/command_storage_manager_delegate.h"
#include "components/tab_groups/tab_group_id.h"
#include "components/tab_groups/tab_group_visual_data.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"

class Profile;

namespace content {
class WebContents;
}  // namespace content

namespace sessions {
struct SessionWindow;
}  // namespace sessions

// SessionService ------------------------------------------------------------

// SessionService is responsible for maintaining the state of open windows
// and tabs so that they can be restored at a later date. The state of the
// currently open browsers is referred to as the current session.
//
// SessionService supports restoring from the last session. The last session
// typically corresponds to the last run of the browser, but not always. For
// example, if the user has a tabbed browser and app window running, closes the
// tabbed browser, then creates a new tabbed browser the current session is made
// the last session and the current session reset. This is done to provide the
// illusion that app windows run in separate processes. Similar behavior occurs
// with incognito windows.
//
// SessionService itself uses functions from session_service_commands to store
// commands which can rebuild the open state of the browser (as |SessionWindow|,
// |SessionTab| and |SerializedNavigationEntry|). The commands are periodically
// flushed to |CommandStorageBackend| and written to a file. Every so often
// |SessionService| rebuilds the contents of the file from the open state of the
// browser.

// TODO(stahon@microsoft.com) When AppSessionService is implemented, we should
// make a pass in SessionService to remove app related code.
class SessionService : public SessionServiceBase,
                       public content::NotificationObserver {
  friend class SessionServiceTestHelper;
 public:
  // Creates a SessionService for the specified profile.
  explicit SessionService(Profile* profile);
  ~SessionService() override;

  // Returns true if a new window opening should really be treated like the
  // start of a session (with potential session restore, startup URLs, etc.).
  // In particular, this is true if there are no tabbed browsers running
  // currently (eg. because only background or other app pages are running).
  bool ShouldNewWindowStartSession();

  // Invoke at a point when you think session restore might occur. For example,
  // during startup and window creation this is invoked to see if a session
  // needs to be restored. If a session needs to be restored it is done so
  // asynchronously and true is returned. If false is returned the session was
  // not restored and the caller needs to create a new window.
  bool RestoreIfNecessary(const std::vector<GURL>& urls_to_open);

  // Moves the current session to the last session. This is useful when a
  // checkpoint occurs, such as when the user launches the app and no tabbed
  // browsers are running.
  void MoveCurrentSessionToLastSession();

  // Deletes the last session.
  void DeleteLastSession();

  // Sets a tab's group ID, if any. Note that a group can't be split between
  // multiple windows.
  void SetTabGroup(const SessionID& window_id,
                   const SessionID& tab_id,
                   base::Optional<tab_groups::TabGroupId> group);

  // Updates the metadata associated with a tab group. |window_id| should be
  // the window where the group currently resides. Note that a group can't be
  // split between multiple windows.
  void SetTabGroupMetadata(const SessionID& window_id,
                           const tab_groups::TabGroupId& group_id,
                           const tab_groups::TabGroupVisualData* visual_data);

  // Sets the pinned state of the tab.
  void SetPinnedState(const SessionID& window_id,
                      const SessionID& tab_id,
                      bool is_pinned);

  void TabClosed(const SessionID& window_id, const SessionID& tab_id) override;

  // Notification a window has opened.
  void WindowOpened(Browser* browser) override;

  // Notification the window is about to close.
  void WindowClosing(const SessionID& window_id) override;

  // Notification a window has finished closing.
  void WindowClosed(const SessionID& window_id) override;

  // Sets the type of window. In order for the contents of a window to be
  // tracked SetWindowType must be invoked with a type we track
  // (ShouldRestoreOfWindowType returns true).
  void SetWindowType(const SessionID& window_id, Browser::Type type) override;

  void SetWindowUserTitle(const SessionID& window_id,
                          const std::string& user_title);

  // Notification that a tab has restored its entries or a closed tab is being
  // reused.
  void TabRestored(content::WebContents* tab, bool pinned);

  // CommandStorageManagerDelegate:
  void OnErrorWritingSessionCommands() override;

  void SetTabUserAgentOverride(const SessionID& window_id,
                               const SessionID& tab_id,
                               const sessions::SerializedUserAgentOverride&
                                   user_agent_override) override;

 private:
  // Allow tests to access our innards for testing purposes.
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, SavedSessionNotification);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, RestoreActivation1);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, RestoreActivation2);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, RemoveUnusedRestoreWindowsTest);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, Workspace);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, WorkspaceSavedOnOpened);
  FRIEND_TEST_ALL_PREFIXES(SessionServiceTest, VisibleOnAllWorkspaces);
  FRIEND_TEST_ALL_PREFIXES(NoStartupWindowTest, DontInitSessionServiceForApps);

  using IdToRange = std::map<SessionID, std::pair<int, int>>;

  // Returns true if a window of given |window_type| should get
  // restored upon session restore.
  bool ShouldRestoreWindowOfType(
      sessions::SessionWindow::WindowType type) const override;

  // Implementation of RestoreIfNecessary. If |browser| is non-null and we
  // need to restore, the tabs are added to it, otherwise a new browser is
  // created.
  bool RestoreIfNecessary(const std::vector<GURL>& urls_to_open,
                          Browser* browser);

  // content::NotificationObserver.
  void Observe(int type,
               const content::NotificationSource& source,
               const content::NotificationDetails& details) override;

  // Adds commands to commands that will recreate the state of the specified
  // tab. This adds at most kMaxNavigationCountToPersist navigations (in each
  // direction from the current navigation index).
  // A pair is added to tab_to_available_range indicating the range of
  // indices that were written.
  void BuildCommandsForTab(const SessionID& window_id,
                           content::WebContents* tab,
                           int index_in_window,
                           base::Optional<tab_groups::TabGroupId> group,
                           bool is_pinned,
                           IdToRange* tab_to_available_range) override;

  // Adds commands to create the specified browser, and invokes
  // BuildCommandsForTab for each of the tabs in the browser. This ignores
  // any tabs not in the profile we were created with.
  void BuildCommandsForBrowser(Browser* browser,
                               IdToRange* tab_to_available_range,
                               std::set<SessionID>* windows_to_track) override;

  // Schedules a reset of the existing commands. A reset means the contents
  // of the file are recreated from the state of the browser.
  void ScheduleResetCommands() override;

  // Converts all pending tab/window closes to commands and schedules them.
  void CommitPendingCloses();

  // Returns true if there is only one window open with a single tab that
  // shares our profile.
  bool IsOnlyOneTabLeft() const;

  // Returns true if there are open trackable browser windows whose ids do
  // match |window_id| with our profile. A trackable window is a window from
  // which |ShouldRestoreWindowOfType| returns true. See
  // |ShouldRestoreWindowOfType| for details.
  bool HasOpenTrackableBrowsers(const SessionID& window_id) const;

  // Returns true if changes to tabs in the specified window should be
  // tracked.
  bool ShouldTrackChangesToWindow(const SessionID& window_id) const override;

  // Will rebuild session commands if rebuild_on_next_save_ is true.
  void RebuildCommandsIfRequired() override;

  // Deletes session data if no windows are open for the current profile.
  void MaybeDeleteSessionOnlyData() override;

  // If necessary, removes the current exit event and adds a new one. This
  // does nothing if `pending_window_close_ids_` is empty, which means the
  // user is potentially closing the last browser.
  void LogExitEvent();

  // If an exit event was logged, it is removed.
  void RemoveExitEvent();

  // When the user closes the last window, where the last window is the
  // last tabbed browser and no more tabbed browsers are open with the same
  // profile, the window ID is added here. These IDs are only committed (which
  // marks them as closed) if the user creates a new tabbed browser.
  using PendingWindowCloseIDs = std::set<SessionID>;
  PendingWindowCloseIDs pending_window_close_ids_;

  // Set of tabs that have been closed by way of the last window or last tab
  // closing, but not yet committed.
  using PendingTabCloseIDs = std::set<SessionID>;
  PendingTabCloseIDs pending_tab_close_ids_;

  // When a window other than the last window (see description of
  // pending_window_close_ids) is closed, the id is added to this set.
  using WindowClosingIDs = std::set<SessionID>;
  WindowClosingIDs window_closing_ids_;

  // Set of windows we're tracking changes to. This is only browsers that
  // return true from |ShouldRestoreWindowOfType|.
  using WindowsTracking = std::set<SessionID>;
  WindowsTracking windows_tracking_;

  // Are there any open trackable browsers?
  bool has_open_trackable_browsers_ = false;

  // Used to override HasOpenTrackableBrowsers()
  bool has_open_trackable_browser_for_test_ = true;

  // Use to override IsOnlyOneTableft()
  bool is_only_one_tab_left_for_test_ = false;

  // If true and a new tabbed browser is created and there are no opened
  // tabbed browser (has_open_trackable_browsers_ is false), then the current
  // session is made the last session. See description above class for details
  // on current/last session.
  bool move_on_new_browser_ = false;

  // For browser_tests, since we want to simulate the browser shutting down
  // without quitting.
  bool force_browser_not_alive_with_no_windows_ = false;

  content::NotificationRegistrar registrar_;

  bool did_log_exit_ = false;

  int unrecoverable_write_error_count_ = 0;

  base::WeakPtrFactory<SessionService> weak_factory_{this};

  DISALLOW_COPY_AND_ASSIGN(SessionService);
};

#endif  // CHROME_BROWSER_SESSIONS_SESSION_SERVICE_H_