Split TabRestoreService into InMemoryTRS and PersistentTRS

chrome/browser/sessions/tab_restore_service_helper.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_TAB_RESTORE_SERVICE_H_
-#define CHROME_BROWSER_SESSIONS_TAB_RESTORE_SERVICE_H_
+#ifndef CHROME_BROWSER_SESSIONS_TAB_RESTORE_SERVICE_HELPER_H_
+#define CHROME_BROWSER_SESSIONS_TAB_RESTORE_SERVICE_HELPER_H_
 
-#include <list>
 #include <set>
-#include <vector>
 
-#include "base/gtest_prod_util.h"
+#include "base/basictypes.h"
 #include "base/observer_list.h"
 #include "base/time.h"
-#include "chrome/browser/sessions/base_session_service.h"
 #include "chrome/browser/sessions/session_id.h"
 #include "chrome/browser/sessions/session_types.h"
-#include "content/public/browser/session_storage_namespace.h"
-#include "webkit/glue/window_open_disposition.h"
+#include "chrome/browser/sessions/tab_restore_service.h"
 
 class Profile;
+class TabRestoreService;
 class TabRestoreServiceDelegate;
 class TabRestoreServiceObserver;
-struct SessionWindow;
+class TimeFactory;
 
 namespace content {
 class NavigationController;
-class SessionStorageNamespace;
 class WebContents;
 }
 
-// TabRestoreService is responsible for maintaining the most recently closed
-// tabs and windows. When a tab is closed
-// TabRestoreService::CreateHistoricalTab is invoked and a Tab is created to
-// represent the tab. Similarly, when a browser is closed, BrowserClosing is
-// invoked and a Window is created to represent the window.
-//
-// To restore a tab/window from the TabRestoreService invoke RestoreEntryById
-// or RestoreMostRecentEntry.
-//
-// To listen for changes to the set of entries managed by the TabRestoreService
-// add an observer.
-class TabRestoreService : public BaseSessionService {
+// Helper class used to implement InMemoryTabRestoreService and
+// PersistentTabRestoreService. See tab_restore_service.h for method-level
+// comments.
+class TabRestoreServiceHelper {
  public:
-  // Interface used to allow the test to provide a custom time.
-  class TimeFactory {
+  typedef TabRestoreService::Entries Entries;
+  typedef TabRestoreService::Entry Entry;
+  typedef TabRestoreService::Tab Tab;
+  typedef TabRestoreService::TimeFactory TimeFactory;
+  typedef TabRestoreService::Window Window;
+
+  // Provides a way for the client to add behavior to the tab restore service
+  // helper (e.g. implementing tabs persistence).
+  class Observer {
    public:
-    virtual ~TimeFactory();
-    virtual base::Time TimeNow() = 0;
+    // Invoked before the entries are cleared.
+    virtual void OnClearEntries();
+
+    // Invoked before the entry is restored. |entry_iterator| points to the
+    // entry corresponding to the session identified by |id|.
+    virtual void OnRestoreEntryById(SessionID::id_type id,
+                                    Entries::const_iterator entry_iterator);
+
+    // Invoked after an entry was added.
+    virtual void OnAddEntry();
+
+   protected:
+    virtual ~Observer();
   };
 
-  // The type of entry.
-  enum Type {
-    TAB,
-    WINDOW
-  };
+  // Max number of entries we'll keep around.
+  static const size_t kMaxEntries;
 
-  struct Entry {
-    Entry();
-    explicit Entry(Type type);
-    virtual ~Entry();
+  // Creates a new TabRestoreServiceHelper and provides an object that provides
+  // the current time. The TabRestoreServiceHelper does not take ownership of
+  // |time_factory| and |observer|. Note that |observer| can also be NULL.
+  TabRestoreServiceHelper(TabRestoreService* tab_restore_service,
+                          Observer* observer,
+                          Profile* profile,
+                          TimeFactory* time_factory);
 
-    // Unique id for this entry. The id is guaranteed to be unique for a
-    // session.
-    SessionID::id_type id;
+  ~TabRestoreServiceHelper();
 
-    // The type of the entry.
-    Type type;
-
-    // The time when the window or tab was closed.
-    base::Time timestamp;
-
-    // Is this entry from the last session? This is set to true for entries that
-    // were closed during the last session, and false for entries that were
-    // closed during this session.
-    bool from_last_session;
-  };
-
-  // Represents a previously open tab.
-  struct Tab : public Entry {
-    Tab();
-    virtual ~Tab();
-
-    bool has_browser() const { return browser_id > 0; }
-
-    // The navigations.
-    std::vector<TabNavigation> navigations;
-
-    // Index of the selected navigation in navigations.
-    int current_navigation_index;
-
-    // The ID of the browser to which this tab belonged, so it can be restored
-    // there. May be 0 (an invalid SessionID) when restoring an entire session.
-    SessionID::id_type browser_id;
-
-    // Index within the tab strip. May be -1 for an unknown index.
-    int tabstrip_index;
-
-    // True if the tab was pinned.
-    bool pinned;
-
-    // If non-empty gives the id of the extension for the tab.
-    std::string extension_app_id;
-
-    // The associated session storage namespace (if any).
-    scoped_refptr<content::SessionStorageNamespace> session_storage_namespace;
-
-    // The user agent override used for the tab's navigations (if applicable).
-    std::string user_agent_override;
-  };
-
-  // Represents a previously open window.
-  struct Window : public Entry {
-    Window();
-    virtual ~Window();
-
-    // The tabs that comprised the window, in order.
-    std::vector<Tab> tabs;
-
-    // Index of the selected tab.
-    int selected_tab_index;
-
-    // If an application window, the name of the app.
-    std::string app_name;
-  };
-
-  typedef std::list<Entry*> Entries;
-
-  // Creates a new TabRestoreService and provides an object that provides the
-  // current time. The TabRestoreService does not take ownership of the
-  // |time_factory_|.
-  TabRestoreService(Profile* profile, TimeFactory* time_factory_ = NULL);
-
-  virtual ~TabRestoreService();
-
-  // Adds/removes an observer. TabRestoreService does not take ownership of
-  // the observer.
+  // Helper methods used to implement TabRestoreService.
   void AddObserver(TabRestoreServiceObserver* observer);
   void RemoveObserver(TabRestoreServiceObserver* observer);
-
-  // Creates a Tab to represent |contents| and notifies observers the list of
-  // entries has changed.
   void CreateHistoricalTab(content::WebContents* contents, int index);
-
-  // Invoked when a browser is closing. If |delegate| is a tabbed browser with
-  // at least one tab, a Window is created, added to entries and observers are
-  // notified.
   void BrowserClosing(TabRestoreServiceDelegate* delegate);
-
-  // Invoked when the browser is done closing.
   void BrowserClosed(TabRestoreServiceDelegate* delegate);
-
-  // Removes all entries from the list and notifies observers the list
-  // of tabs has changed.
   void ClearEntries();
-
-  // Returns the entries, ordered with most recently closed entries at the
-  // front.
-  virtual const Entries& entries() const;
-
-  // Restores the most recently closed entry. Does nothing if there are no
-  // entries to restore. If the most recently restored entry is a tab, it is
-  // added to |delegate|.
+  const Entries& entries() const;
   void RestoreMostRecentEntry(TabRestoreServiceDelegate* delegate);
-
-  // Removes the Tab with id |id| from the list and returns it; ownership is
-  // passed to the caller.
   Tab* RemoveTabEntryById(SessionID::id_type id);
-
-  // Restores an entry by id. If there is no entry with an id matching |id|,
-  // this does nothing. If |delegate| is NULL, this creates a new window for the
-  // entry. |disposition| is respected, but the attributes (tabstrip index,
-  // browser window) of the tab when it was closed will be respected if
-  // disposition is UNKNOWN.
   void RestoreEntryById(TabRestoreServiceDelegate* delegate,
                         SessionID::id_type id,
                         WindowOpenDisposition disposition);
 
-  // Loads the tabs and previous session. This does nothing if the tabs
-  // from the previous session have already been loaded.
-  void LoadTabsFromLastSession();
-
-  // Returns true if the tab entries have been loaded.
-  bool IsLoaded() const;
-
-  // Max number of entries we'll keep around.
-  static const size_t kMaxEntries;
-
-  // Creates and add entries to |entries| for each of the windows in |windows|.
-  void CreateEntriesFromWindows(std::vector<SessionWindow*>* windows,
-                                std::vector<Entry*>* entries);
-
- protected:
-  // ProfileKeyedService:
-  virtual void Shutdown() OVERRIDE;
-
-  // BaseSessionService:
-  virtual void Save() OVERRIDE;
-
- private:
-  friend class TabRestoreServiceTest;
-  FRIEND_TEST_ALL_PREFIXES(TabRestoreServiceTest, PruneEntries);
-  FRIEND_TEST_ALL_PREFIXES(TabRestoreServiceTest, PruneIsCalled);
-
-  // Used to indicate what has loaded.
-  enum LoadState {
-    // Indicates we haven't loaded anything.
-    NOT_LOADED           = 1 << 0,
-
-    // Indicates we've asked for the last sessions and tabs but haven't gotten
-    // the result back yet.
-    LOADING              = 1 << 2,
-
-    // Indicates we finished loading the last tabs (but not necessarily the
-    // last session).
-    LOADED_LAST_TABS     = 1 << 3,
-
-    // Indicates we finished loading the last session (but not necessarily the
-    // last tabs).
-    LOADED_LAST_SESSION  = 1 << 4
-  };
-
-  // Populates the tab's navigations from the NavigationController, and its
-  // browser_id and pinned state from the browser.
-  void PopulateTab(Tab* tab,
-                   int index,
-                   TabRestoreServiceDelegate* delegate,
-                   content::NavigationController* controller);
-
   // Notifies observers the tabs have changed.
   void NotifyTabsChanged();
 
   // Adds |entry| to the list of entries and takes ownership. If |prune| is true
   // |PruneAndNotify| is invoked. If |to_front| is true the entry is added to
   // the front, otherwise the back. Normal closes go to the front, but
   // tab/window closes from the previous session are added to the back.
   void AddEntry(Entry* entry, bool prune, bool to_front);
 
-  // Prunes entries_ to contain only kMaxEntries, and removes uninteresting
+  // Prunes |entries_| to contain only kMaxEntries, and removes uninteresting
   // entries.
   void PruneEntries();
 
-  // Returns an iterator into entries_ whose id matches |id|. If |id| identifies
-  // a Window, then its iterator position will be returned. If it identifies a
-  // tab, then the iterator position of the Window in which the Tab resides is
-  // returned.
+  // Returns an iterator into |entries_| whose id matches |id|. If |id|
+  // identifies a Window, then its iterator position will be returned. If it
+  // identifies a tab, then the iterator position of the Window in which the Tab
+  // resides is returned.
   Entries::iterator GetEntryIteratorById(SessionID::id_type id);
 
-  // Schedules the commands for a window close.
-  void ScheduleCommandsForWindow(const Window& window);
+  // Calls either ValidateTab or ValidateWindow as appropriate.
+  static bool ValidateEntry(Entry* entry);
 
-  // Schedules the commands for a tab close. |selected_index| gives the
-  // index of the selected navigation.
-  void ScheduleCommandsForTab(const Tab& tab, int selected_index);
+ private:
+  friend class PersistentTabRestoreService;
 
-  // Creates a window close command.
-  SessionCommand* CreateWindowCommand(SessionID::id_type id,
-                                      int selected_tab_index,
-                                      int num_tabs,
-                                      base::Time timestamp);
-
-  // Creates a tab close command.
-  SessionCommand* CreateSelectedNavigationInTabCommand(
-      SessionID::id_type tab_id,
-      int32 index,
-      base::Time timestamp);
-
-  // Creates a restore command.
-  SessionCommand* CreateRestoredEntryCommand(SessionID::id_type entry_id);
-
-  // Returns the index to persist as the selected index. This is the same
-  // as |tab.current_navigation_index| unless the entry at
-  // |tab.current_navigation_index| shouldn't be persisted. Returns -1 if
-  // no valid navigation to persist.
-  int GetSelectedNavigationIndexToPersist(const Tab& tab);
-
-  // Invoked when we've loaded the session commands that identify the
-  // previously closed tabs. This creates entries, adds them to
-  // staging_entries_, and invokes LoadState.
-  void OnGotLastSessionCommands(
-      Handle handle,
-      scoped_refptr<InternalGetCommandsRequest> request);
-
-  // Populates |loaded_entries| with Entries from |request|.
-  void CreateEntriesFromCommands(
-      scoped_refptr<InternalGetCommandsRequest> request,
-      std::vector<Entry*>* loaded_entries);
+  // Populates the tab's navigations from the NavigationController, and its
+  // browser_id and pinned state from the browser.
+  void PopulateTab(Tab* tab,
+                   int index,
+                   TabRestoreServiceDelegate* delegate,
+                   content::NavigationController* controller);
 
   // This is a helper function for RestoreEntryById() for restoring a single
   // tab. If |delegate| is NULL, this creates a new window for the entry. This
   // returns the TabRestoreServiceDelegate into which the tab was restored.
   // |disposition| will be respected, but if it is UNKNOWN then the tab's
   // original attributes will be respected instead.
   TabRestoreServiceDelegate* RestoreTab(const Tab& tab,
                                         TabRestoreServiceDelegate* delegate,
                                         WindowOpenDisposition disposition);
 
   // Returns true if |tab| has more than one navigation. If |tab| has more
   // than one navigation |tab->current_navigation_index| is constrained based
   // on the number of navigations.
   static bool ValidateTab(Tab* tab);
 
   // Validates all the tabs in a window, plus the window's active tab index.
   static bool ValidateWindow(Window* window);
 
-  // Calls either ValidateTab or ValidateWindow as appropriate.
-  static bool ValidateEntry(Entry* entry);
-
   // Returns true if |tab| is one we care about restoring.
   static bool IsTabInteresting(const Tab* tab);
 
   // Checks whether |window| is interesting --- if it only contains a single,
   // uninteresting tab, it's not interesting.
   static bool IsWindowInteresting(const Window* window);
 
   // Validates and checks |entry| for interesting.
   static bool FilterEntry(Entry* entry);
 
-  // Validates all entries in |entries|, deleting any with no navigations.
-  // This also deletes any entries beyond the max number of entries we can
-  // hold.
-  void ValidateAndDeleteEmptyEntries(std::vector<Entry*>* entries);
-
   // Finds tab entries with the old browser_id and sets it to the new one.
   void UpdateTabBrowserIDs(SessionID::id_type old_id,
                            SessionID::id_type new_id);
 
-  // Callback from SessionService when we've received the windows from the
-  // previous session. This creates and add entries to |staging_entries_|
-  // and invokes LoadStateChanged. |ignored_active_window| is ignored because
-  // we don't need to restore activation.
-  void OnGotPreviousSession(Handle handle,
-                            std::vector<SessionWindow*>* windows,
-                            SessionID::id_type ignored_active_window);
-
-  // Converts a SessionWindow into a Window, returning true on success. We use 0
-  // as the timestamp here since we do not know when the window/tab was closed.
-  bool ConvertSessionWindowToWindow(
-      SessionWindow* session_window,
-      Window* window);
-
-  // Invoked when previous tabs or session is loaded. If both have finished
-  // loading the entries in staging_entries_ are added to entries_ and
-  // observers are notified.
-  void LoadStateChanged();
-
   // Gets the current time. This uses the time_factory_ if there is one.
   base::Time TimeNow() const;
 
+  TabRestoreService* const tab_restore_service_;
+
+  Observer* const observer_;
+
+  Profile* const profile_;
+
   // Set of entries. They are ordered from most to least recent.
   Entries entries_;
 
-  // Whether we've loaded the last session.
-  int load_state_;
-
   // Are we restoring a tab? If this is true we ignore requests to create a
   // historical tab.
   bool restoring_;
 
-  // The number of entries to write.
-  int entries_to_write_;
-
-  // Number of entries we've written.
-  int entries_written_;
-
   ObserverList<TabRestoreServiceObserver> observer_list_;
 
   // Set of delegates that we've received a BrowserClosing method for but no
   // corresponding BrowserClosed. We cache the set of delegates closing to
   // avoid creating historical tabs for them.
   std::set<TabRestoreServiceDelegate*> closing_delegates_;
 
-  // Used when loading open tabs/session when recovering from a crash.
-  CancelableRequestConsumer crash_consumer_;
+  TimeFactory* const time_factory_;
 
-  // Used when loading previous tabs/session.
-  CancelableRequestConsumer load_consumer_;
-
-  // Results from previously closed tabs/sessions is first added here. When
-  // the results from both us and the session restore service have finished
-  // loading LoadStateChanged is invoked, which adds these entries to
-  // entries_.
-  std::vector<Entry*> staging_entries_;
-
-  TimeFactory* time_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(TabRestoreService);
+  DISALLOW_COPY_AND_ASSIGN(TabRestoreServiceHelper);
 };
 
-#endif  // CHROME_BROWSER_SESSIONS_TAB_RESTORE_SERVICE_H_
+#endif  // CHROME_BROWSER_SESSIONS_TAB_RESTORE_SERVICE_HELPER_H_