Split TabRestoreService into InMemoryTRS and PersistentTRS

chrome/browser/sessions/tab_restore_service_helper.cc

Index: chrome/browser/sessions/tab_restore_service_helper.cc
diff --git a/chrome/browser/sessions/tab_restore_service.cc b/chrome/browser/sessions/tab_restore_service_helper.cc
similarity index 33%
copy from chrome/browser/sessions/tab_restore_service.cc
copy to chrome/browser/sessions/tab_restore_service_helper.cc
index 4003edb3ad7f707fa978dfab25a33896f38fcf50..27e841a47e266f2d474a5eb2da6a04e4a5d4a25b 100644
--- a/chrome/browser/sessions/tab_restore_service.cc
+++ b/chrome/browser/sessions/tab_restore_service_helper.cc
@@ -2,24 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "chrome/browser/sessions/tab_restore_service.h"
+#include "chrome/browser/sessions/tab_restore_service_helper.h"
 
 #include <algorithm>
 #include <iterator>
-#include <map>
 
-#include "base/bind.h"
-#include "base/bind_helpers.h"
-#include "base/callback.h"
-#include "base/memory/scoped_vector.h"
+#include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/tab_helper.h"
 #include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/sessions/session_command.h"
-#include "chrome/browser/sessions/session_service.h"
-#include "chrome/browser/sessions/session_service_factory.h"
 #include "chrome/browser/sessions/session_types.h"
 #include "chrome/browser/sessions/tab_restore_service_delegate.h"
 #include "chrome/browser/sessions/tab_restore_service_observer.h"
@@ -31,139 +24,16 @@
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/browser/session_storage_namespace.h"
 
-using base::Time;
 using content::NavigationController;
 using content::NavigationEntry;
 using content::WebContents;
 
-// TimeFactory-----------------------------------------------------------------
-
-TabRestoreService::TimeFactory::~TimeFactory() {}
-
-// Entry ----------------------------------------------------------------------
-
-// ID of the next Entry.
-static SessionID::id_type next_entry_id = 1;
-
-TabRestoreService::Entry::Entry()
-    : id(next_entry_id++),
-      type(TAB),
-      from_last_session(false) {}
-
-TabRestoreService::Entry::Entry(Type type)
-    : id(next_entry_id++),
-      type(type),
-      from_last_session(false) {}
-
-TabRestoreService::Entry::~Entry() {}
-
-// TabRestoreService ----------------------------------------------------------
-
-// static
-const size_t TabRestoreService::kMaxEntries = 25;
-
-// Identifier for commands written to file.
-// The ordering in the file is as follows:
-// . When the user closes a tab a command of type
-//   kCommandSelectedNavigationInTab is written identifying the tab and
-//   the selected index, then a kCommandPinnedState command if the tab was
-//   pinned and kCommandSetExtensionAppID if the tab has an app id and
-//   the user agent override if it was using one.  This is
-//   followed by any number of kCommandUpdateTabNavigation commands (1 per
-//   navigation entry).
-// . When the user closes a window a kCommandSelectedNavigationInTab command
-//   is written out and followed by n tab closed sequences (as previoulsy
-//   described).
-// . When the user restores an entry a command of type kCommandRestoredEntry
-//   is written.
-static const SessionCommand::id_type kCommandUpdateTabNavigation = 1;
-static const SessionCommand::id_type kCommandRestoredEntry = 2;
-static const SessionCommand::id_type kCommandWindow = 3;
-static const SessionCommand::id_type kCommandSelectedNavigationInTab = 4;
-static const SessionCommand::id_type kCommandPinnedState = 5;
-static const SessionCommand::id_type kCommandSetExtensionAppID = 6;
-static const SessionCommand::id_type kCommandSetWindowAppName = 7;
-static const SessionCommand::id_type kCommandSetTabUserAgentOverride = 8;
-
-// Number of entries (not commands) before we clobber the file and write
-// everything.
-static const int kEntriesPerReset = 40;
-
 namespace {
 
-// Payload structures.
-
-typedef int32 RestoredEntryPayload;
-
-// Payload used for the start of a window close. This is the old struct that is
-// used for backwards compat when it comes to reading the session files. This
-// struct must be POD, because we memset the contents.
-struct WindowPayload {
-  SessionID::id_type window_id;
-  int32 selected_tab_index;
-  int32 num_tabs;
-};
-
-// Payload used for the start of a tab close. This is the old struct that is
-// used for backwards compat when it comes to reading the session files.
-struct SelectedNavigationInTabPayload {
-  SessionID::id_type id;
-  int32 index;
-};
-
-// Payload used for the start of a window close.  This struct must be POD,
-// because we memset the contents.
-struct WindowPayload2 : WindowPayload {
-  int64 timestamp;
-};
-
-// Payload used for the start of a tab close.
-struct SelectedNavigationInTabPayload2 : SelectedNavigationInTabPayload {
-  int64 timestamp;
-};
-
-// Only written if the tab is pinned.
-typedef bool PinnedStatePayload;
-
-typedef std::map<SessionID::id_type, TabRestoreService::Entry*> IDToEntry;
-
-// If |id_to_entry| contains an entry for |id| the corresponding entry is
-// deleted and removed from both |id_to_entry| and |entries|. This is used
-// when creating entries from the backend file.
-void RemoveEntryByID(SessionID::id_type id,
-                     IDToEntry* id_to_entry,
-                     std::vector<TabRestoreService::Entry*>* entries) {
-  // Look for the entry in the map. If it is present, erase it from both
-  // collections and return.
-  IDToEntry::iterator i = id_to_entry->find(id);
-  if (i != id_to_entry->end()) {
-    entries->erase(std::find(entries->begin(), entries->end(), i->second));
-    delete i->second;
-    id_to_entry->erase(i);
-    return;
-  }
-
-  // Otherwise, loop over all items in the map and see if any of the Windows
-  // have Tabs with the |id|.
-  for (IDToEntry::iterator i = id_to_entry->begin(); i != id_to_entry->end();
-       ++i) {
-    if (i->second->type == TabRestoreService::WINDOW) {
-      TabRestoreService::Window* window =
-          static_cast<TabRestoreService::Window*>(i->second);
-      std::vector<TabRestoreService::Tab>::iterator j = window->tabs.begin();
-      for ( ; j != window->tabs.end(); ++j) {
-        // If the ID matches one of this window's tabs, remove it from the list.
-        if ((*j).id == id) {
-          window->tabs.erase(j);
-          return;
-        }
-      }
-    }
-  }
-}
-
 void RecordAppLaunch(Profile* profile, const TabRestoreService::Tab& tab) {
+#if !defined(OS_ANDROID)
   GURL url = tab.navigations.at(tab.current_navigation_index).virtual_url();
   DCHECK(profile->GetExtensionService());
   if (!profile->GetExtensionService()->IsInstalledApp(url))
@@ -171,56 +41,60 @@ void RecordAppLaunch(Profile* profile, const TabRestoreService::Tab& tab) {
 
   AppLauncherHandler::RecordAppLaunchType(
       extension_misc::APP_LAUNCH_NTP_RECENTLY_CLOSED);
+#endif  // !defined(OS_ANDROID)
 }
 
 }  // namespace
 
-TabRestoreService::Tab::Tab()
-    : Entry(TAB),
-      current_navigation_index(-1),
-      browser_id(0),
-      tabstrip_index(-1),
-      pinned(false) {
-}
+// TabRestoreServiceHelper::Observer -------------------------------------------
 
-TabRestoreService::Tab::~Tab() {
-}
+TabRestoreServiceHelper::Observer::~Observer() {}
 
-TabRestoreService::Window::Window() : Entry(WINDOW), selected_tab_index(-1) {
-}
+void TabRestoreServiceHelper::Observer::OnClearEntries() {}
 
-TabRestoreService::Window::~Window() {
+void TabRestoreServiceHelper::Observer::OnRestoreEntryById(
+    SessionID::id_type id,
+    Entries::const_iterator entry_iterator) {
 }
 
-TabRestoreService::TabRestoreService(Profile* profile,
+void TabRestoreServiceHelper::Observer::OnAddEntry() {}
+
+// TabRestoreServiceHelper -----------------------------------------------------
+
+const size_t TabRestoreServiceHelper::kMaxEntries = 25;
+
+TabRestoreServiceHelper::TabRestoreServiceHelper(
+    TabRestoreService* tab_restore_service,
+    Observer* observer,
+    Profile* profile,
     TabRestoreService::TimeFactory* time_factory)
-    : BaseSessionService(BaseSessionService::TAB_RESTORE, profile,
-                         FilePath()),
-      load_state_(NOT_LOADED),
+    : tab_restore_service_(tab_restore_service),
+      observer_(observer),
+      profile_(profile),
       restoring_(false),
-      entries_to_write_(0),
-      entries_written_(0),
       time_factory_(time_factory) {
+  DCHECK(tab_restore_service_);
 }
 
-TabRestoreService::~TabRestoreService() {
+TabRestoreServiceHelper::~TabRestoreServiceHelper() {
   FOR_EACH_OBSERVER(TabRestoreServiceObserver, observer_list_,
-                    TabRestoreServiceDestroyed(this));
+                    TabRestoreServiceDestroyed(tab_restore_service_));
   STLDeleteElements(&entries_);
-  STLDeleteElements(&staging_entries_);
-  time_factory_ = NULL;
 }
 
-void TabRestoreService::AddObserver(TabRestoreServiceObserver* observer) {
+void TabRestoreServiceHelper::AddObserver(
+    TabRestoreServiceObserver* observer) {
   observer_list_.AddObserver(observer);
 }
 
-void TabRestoreService::RemoveObserver(TabRestoreServiceObserver* observer) {
+void TabRestoreServiceHelper::RemoveObserver(
+    TabRestoreServiceObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
-void TabRestoreService::CreateHistoricalTab(content::WebContents* contents,
-                                            int index) {
+void TabRestoreServiceHelper::CreateHistoricalTab(
+    content::WebContents* contents,
+    int index) {
   if (restoring_)
     return;
 
@@ -237,7 +111,8 @@ void TabRestoreService::CreateHistoricalTab(content::WebContents* contents,
   AddEntry(local_tab.release(), true, true);
 }
 
-void TabRestoreService::BrowserClosing(TabRestoreServiceDelegate* delegate) {
+void TabRestoreServiceHelper::BrowserClosing(
+    TabRestoreServiceDelegate* delegate) {
   closing_delegates_.insert(delegate);
 
   scoped_ptr<Window> window(new Window());
@@ -276,33 +151,23 @@ void TabRestoreService::BrowserClosing(TabRestoreServiceDelegate* delegate) {
   }
 }
 
-void TabRestoreService::BrowserClosed(TabRestoreServiceDelegate* delegate) {
+void TabRestoreServiceHelper::BrowserClosed(
+    TabRestoreServiceDelegate* delegate) {
   closing_delegates_.erase(delegate);
 }
 
-void TabRestoreService::ClearEntries() {
-  // Mark all the tabs as closed so that we don't attempt to restore them.
-  for (Entries::iterator i = entries_.begin(); i != entries_.end(); ++i)
-    ScheduleCommand(CreateRestoredEntryCommand((*i)->id));
-
-  entries_to_write_ = 0;
-
-  // Schedule a pending reset so that we nuke the file on next write.
-  set_pending_reset(true);
-
-  // Schedule a command, otherwise if there are no pending commands Save does
-  // nothing.
-  ScheduleCommand(CreateRestoredEntryCommand(1));
-
+void TabRestoreServiceHelper::ClearEntries() {
+  if (observer_)
+    observer_->OnClearEntries();
   STLDeleteElements(&entries_);
   NotifyTabsChanged();
 }
 
-const TabRestoreService::Entries& TabRestoreService::entries() const {
+const TabRestoreService::Entries& TabRestoreServiceHelper::entries() const {
   return entries_;
 }
 
-void TabRestoreService::RestoreMostRecentEntry(
+void TabRestoreServiceHelper::RestoreMostRecentEntry(
     TabRestoreServiceDelegate* delegate) {
   if (entries_.empty())
     return;
@@ -310,14 +175,14 @@ void TabRestoreService::RestoreMostRecentEntry(
   RestoreEntryById(delegate, entries_.front()->id, UNKNOWN);
 }
 
-TabRestoreService::Tab* TabRestoreService::RemoveTabEntryById(
+TabRestoreService::Tab* TabRestoreServiceHelper::RemoveTabEntryById(
     SessionID::id_type id) {
   Entries::iterator i = GetEntryIteratorById(id);
   if (i == entries_.end())
     return NULL;
 
   Entry* entry = *i;
-  if (entry->type != TAB)
+  if (entry->type != TabRestoreService::TAB)
     return NULL;
 
   Tab* tab = static_cast<Tab*>(entry);
@@ -325,43 +190,37 @@ TabRestoreService::Tab* TabRestoreService::RemoveTabEntryById(
   return tab;
 }
 
-void TabRestoreService::RestoreEntryById(TabRestoreServiceDelegate* delegate,
-                                         SessionID::id_type id,
-                                         WindowOpenDisposition disposition) {
-  Entries::iterator i = GetEntryIteratorById(id);
-  if (i == entries_.end()) {
+void TabRestoreServiceHelper::RestoreEntryById(
+    TabRestoreServiceDelegate* delegate,
+    SessionID::id_type id,
+    WindowOpenDisposition disposition) {
+  Entries::iterator entry_iterator = GetEntryIteratorById(id);
+  if (entry_iterator == entries_.end())
     // Don't hoark here, we allow an invalid id.
     return;
-  }
-
-  size_t index = 0;
-  for (Entries::iterator j = entries_.begin(); j != i && j != entries_.end();
-       ++j, ++index) {}
-  if (static_cast<int>(index) < entries_to_write_)
-    entries_to_write_--;
-
-  ScheduleCommand(CreateRestoredEntryCommand(id));
 
+  if (observer_)
+    observer_->OnRestoreEntryById(id, entry_iterator);
   restoring_ = true;
-  Entry* entry = *i;
+  Entry* entry = *entry_iterator;
 
   // If the entry's ID does not match the ID that is being restored, then the
   // entry is a window from which a single tab will be restored.
   bool restoring_tab_in_window = entry->id != id;
 
   if (!restoring_tab_in_window) {
-    entries_.erase(i);
-    i = entries_.end();
+    entries_.erase(entry_iterator);
+    entry_iterator = entries_.end();
   }
 
   // |delegate| will be NULL in cases where one isn't already available (eg,
   // when invoked on Mac OS X with no windows open). In this case, create a
   // new browser into which we restore the tabs.
-  if (entry->type == TAB) {
+  if (entry->type == TabRestoreService::TAB) {
     Tab* tab = static_cast<Tab*>(entry);
     delegate = RestoreTab(*tab, delegate, disposition);
     delegate->ShowBrowserWindow();
-  } else if (entry->type == WINDOW) {
+  } else if (entry->type == TabRestoreService::WINDOW) {
     TabRestoreServiceDelegate* current_delegate = delegate;
     Window* window = static_cast<Window*>(entry);
 
@@ -369,7 +228,7 @@ void TabRestoreService::RestoreEntryById(TabRestoreServiceDelegate* delegate,
     // single tab within it. If the entry's ID matches the one to restore, then
     // the entire window will be restored.
     if (!restoring_tab_in_window) {
-      delegate = TabRestoreServiceDelegate::Create(profile(), window->app_name);
+      delegate = TabRestoreServiceDelegate::Create(profile_, window->app_name);
       for (size_t tab_i = 0; tab_i < window->tabs.size(); ++tab_i) {
         const Tab& tab = window->tabs[tab_i];
         WebContents* restored_tab =
@@ -383,7 +242,7 @@ void TabRestoreService::RestoreEntryById(TabRestoreServiceDelegate* delegate,
                                      tab.user_agent_override);
         if (restored_tab) {
           restored_tab->GetController().LoadIfNecessary();
-          RecordAppLaunch(profile(), tab);
+          RecordAppLaunch(profile_, tab);
         }
       }
       // All the window's tabs had the same former browser_id.
@@ -403,7 +262,7 @@ void TabRestoreService::RestoreEntryById(TabRestoreServiceDelegate* delegate,
           // If restoring the tab leaves the window with nothing else, delete it
           // as well.
           if (!window->tabs.size()) {
-            entries_.erase(i);
+            entries_.erase(entry_iterator);
             delete entry;
           } else {
             // Update the browser ID of the rest of the tabs in the window so if
@@ -438,140 +297,14 @@ void TabRestoreService::RestoreEntryById(TabRestoreServiceDelegate* delegate,
   NotifyTabsChanged();
 }
 
-void TabRestoreService::LoadTabsFromLastSession() {
-  if (load_state_ != NOT_LOADED || entries_.size() == kMaxEntries)
-    return;
-
-#if !defined(ENABLE_SESSION_SERVICE)
-  // If sessions are not stored in the SessionService, default to
-  // |LOADED_LAST_SESSION| state.
-  load_state_ = LOADING | LOADED_LAST_SESSION;
-#else
-  load_state_ = LOADING;
-
-  SessionService* session_service =
-      SessionServiceFactory::GetForProfile(profile());
-  Profile::ExitType exit_type = profile()->GetLastSessionExitType();
-  if (!profile()->restored_last_session() && session_service &&
-      (exit_type == Profile::EXIT_CRASHED ||
-       exit_type == Profile::EXIT_SESSION_ENDED)) {
-    // The previous session crashed and wasn't restored, or was a forced
-    // shutdown. Both of which won't have notified us of the browser close so
-    // that we need to load the windows from session service (which will have
-    // saved them).
-    session_service->GetLastSession(
-        &crash_consumer_,
-        base::Bind(&TabRestoreService::OnGotPreviousSession,
-                   base::Unretained(this)));
-  } else {
-    load_state_ |= LOADED_LAST_SESSION;
-  }
-#endif
-
-  // Request the tabs closed in the last session. If the last session crashed,
-  // this won't contain the tabs/window that were open at the point of the
-  // crash (the call to GetLastSession above requests those).
-  ScheduleGetLastSessionCommands(
-      new InternalGetCommandsRequest(
-          base::Bind(&TabRestoreService::OnGotLastSessionCommands,
-                     base::Unretained(this))),
-      &load_consumer_);
-}
-
-bool TabRestoreService::IsLoaded() const {
-  return !(load_state_ & (NOT_LOADED | LOADING));
-}
-
-void TabRestoreService::Shutdown() {
-  if (backend())
-    Save();
-}
-
-void TabRestoreService::Save() {
-  int to_write_count = std::min(entries_to_write_,
-                                static_cast<int>(entries_.size()));
-  entries_to_write_ = 0;
-  if (entries_written_ + to_write_count > kEntriesPerReset) {
-    to_write_count = entries_.size();
-    set_pending_reset(true);
-  }
-  if (to_write_count) {
-    // Write the to_write_count most recently added entries out. The most
-    // recently added entry is at the front, so we use a reverse iterator to
-    // write in the order the entries were added.
-    Entries::reverse_iterator i = entries_.rbegin();
-    DCHECK(static_cast<size_t>(to_write_count) <= entries_.size());
-    std::advance(i, entries_.size() - static_cast<int>(to_write_count));
-    for (; i != entries_.rend(); ++i) {
-      Entry* entry = *i;
-      if (entry->type == TAB) {
-        Tab* tab = static_cast<Tab*>(entry);
-        int selected_index = GetSelectedNavigationIndexToPersist(*tab);
-        if (selected_index != -1)
-          ScheduleCommandsForTab(*tab, selected_index);
-      } else {
-        ScheduleCommandsForWindow(*static_cast<Window*>(entry));
-      }
-      entries_written_++;
-    }
-  }
-  if (pending_reset())
-    entries_written_ = 0;
-  BaseSessionService::Save();
-}
-
-void TabRestoreService::PopulateTab(Tab* tab,
-                                    int index,
-                                    TabRestoreServiceDelegate* delegate,
-                                    NavigationController* controller) {
-  const int pending_index = controller->GetPendingEntryIndex();
-  int entry_count = controller->GetEntryCount();
-  if (entry_count == 0 && pending_index == 0)
-    entry_count++;
-  tab->navigations.resize(static_cast<int>(entry_count));
-  for (int i = 0; i < entry_count; ++i) {
-    NavigationEntry* entry = (i == pending_index) ?
-        controller->GetPendingEntry() : controller->GetEntryAtIndex(i);
-    tab->navigations[i] =
-        TabNavigation::FromNavigationEntry(i, *entry);
-  }
-  tab->timestamp = TimeNow();
-  tab->current_navigation_index = controller->GetCurrentEntryIndex();
-  if (tab->current_navigation_index == -1 && entry_count > 0)
-    tab->current_navigation_index = 0;
-  tab->tabstrip_index = index;
-
-  TabContents* tab_contents =
-      TabContents::FromWebContents(controller->GetWebContents());
-  // tab_contents is NULL in some browser tests.
-  if (tab_contents) {
-    const extensions::Extension* extension =
-        extensions::TabHelper::FromWebContents(controller->GetWebContents())->
-            extension_app();
-    if (extension)
-      tab->extension_app_id = extension->id();
-  }
-
-  tab->user_agent_override =
-      controller->GetWebContents()->GetUserAgentOverride();
-
-  // TODO(ajwong): This does not correctly handle storage for isolated apps.
-  tab->session_storage_namespace =
-      controller->GetDefaultSessionStorageNamespace();
-
-  // Delegate may be NULL during unit tests.
-  if (delegate) {
-    tab->browser_id = delegate->GetSessionID().id();
-    tab->pinned = delegate->IsTabPinned(tab->tabstrip_index);
-  }
-}
-
-void TabRestoreService::NotifyTabsChanged() {
+void TabRestoreServiceHelper::NotifyTabsChanged() {
   FOR_EACH_OBSERVER(TabRestoreServiceObserver, observer_list_,
-                    TabRestoreServiceChanged(this));
+                    TabRestoreServiceChanged(tab_restore_service_));
 }
 
-void TabRestoreService::AddEntry(Entry* entry, bool notify, bool to_front) {
+void TabRestoreServiceHelper::AddEntry(Entry* entry,
+                                       bool notify,
+                                       bool to_front) {
   if (!FilterEntry(entry) || (entries_.size() >= kMaxEntries && !to_front)) {
     delete entry;
     return;
@@ -587,12 +320,11 @@ void TabRestoreService::AddEntry(Entry* entry, bool notify, bool to_front) {
   if (notify)
     NotifyTabsChanged();
 
-  // Start the save timer, when it fires we'll generate the commands.
-  StartSaveTimer();
-  entries_to_write_++;
+  if (observer_)
+    observer_->OnAddEntry();
 }
 
-void TabRestoreService::PruneEntries() {
+void TabRestoreServiceHelper::PruneEntries() {
   Entries new_entries;
 
   for (TabRestoreService::Entries::const_iterator iter = entries_.begin();
@@ -610,15 +342,15 @@ void TabRestoreService::PruneEntries() {
   entries_ = new_entries;
 }
 
-TabRestoreService::Entries::iterator TabRestoreService::GetEntryIteratorById(
-    SessionID::id_type id) {
+TabRestoreService::Entries::iterator
+TabRestoreServiceHelper::GetEntryIteratorById(SessionID::id_type id) {
   for (Entries::iterator i = entries_.begin(); i != entries_.end(); ++i) {
     if ((*i)->id == id)
       return i;
 
     // For Window entries, see if the ID matches a tab. If so, report the window
     // as the Entry.
-    if ((*i)->type == WINDOW) {
+    if ((*i)->type == TabRestoreService::WINDOW) {
       std::vector<Tab>& tabs = static_cast<Window*>(*i)->tabs;
       for (std::vector<Tab>::iterator j = tabs.begin();
            j != tabs.end(); ++j) {
@@ -631,368 +363,66 @@ TabRestoreService::Entries::iterator TabRestoreService::GetEntryIteratorById(
   return entries_.end();
 }
 
-void TabRestoreService::ScheduleCommandsForWindow(const Window& window) {
-  DCHECK(!window.tabs.empty());
-  int selected_tab = window.selected_tab_index;
-  int valid_tab_count = 0;
-  int real_selected_tab = selected_tab;
-  for (size_t i = 0; i < window.tabs.size(); ++i) {
-    if (GetSelectedNavigationIndexToPersist(window.tabs[i]) != -1) {
-      valid_tab_count++;
-    } else if (static_cast<int>(i) < selected_tab) {
-      real_selected_tab--;
-    }
-  }
-  if (valid_tab_count == 0)
-    return;  // No tabs to persist.
-
-  ScheduleCommand(
-      CreateWindowCommand(window.id,
-                          std::min(real_selected_tab, valid_tab_count - 1),
-                          valid_tab_count,
-                          window.timestamp));
-
-  if (!window.app_name.empty()) {
-    ScheduleCommand(
-        CreateSetWindowAppNameCommand(kCommandSetWindowAppName,
-                                      window.id,
-                                      window.app_name));
-  }
-
-  for (size_t i = 0; i < window.tabs.size(); ++i) {
-    int selected_index = GetSelectedNavigationIndexToPersist(window.tabs[i]);
-    if (selected_index != -1)
-      ScheduleCommandsForTab(window.tabs[i], selected_index);
-  }
-}
-
-void TabRestoreService::ScheduleCommandsForTab(const Tab& tab,
-                                               int selected_index) {
-  const std::vector<TabNavigation>& navigations = tab.navigations;
-  int max_index = static_cast<int>(navigations.size());
-
-  // Determine the first navigation we'll persist.
-  int valid_count_before_selected = 0;
-  int first_index_to_persist = selected_index;
-  for (int i = selected_index - 1; i >= 0 &&
-       valid_count_before_selected < max_persist_navigation_count; --i) {
-    if (ShouldTrackEntry(navigations[i].virtual_url())) {
-      first_index_to_persist = i;
-      valid_count_before_selected++;
-    }
-  }
-
-  // Write the command that identifies the selected tab.
-  ScheduleCommand(
-      CreateSelectedNavigationInTabCommand(tab.id,
-                                           valid_count_before_selected,
-                                           tab.timestamp));
-
-  if (tab.pinned) {
-    PinnedStatePayload payload = true;
-    SessionCommand* command =
-        new SessionCommand(kCommandPinnedState, sizeof(payload));
-    memcpy(command->contents(), &payload, sizeof(payload));
-    ScheduleCommand(command);
-  }
-
-  if (!tab.extension_app_id.empty()) {
-    ScheduleCommand(
-        CreateSetTabExtensionAppIDCommand(kCommandSetExtensionAppID, tab.id,
-                                          tab.extension_app_id));
-  }
-
-  if (!tab.user_agent_override.empty()) {
-    ScheduleCommand(
-        CreateSetTabUserAgentOverrideCommand(kCommandSetTabUserAgentOverride,
-                                             tab.id, tab.user_agent_override));
-  }
-
-  // Then write the navigations.
-  for (int i = first_index_to_persist, wrote_count = 0;
-       i < max_index && wrote_count < 2 * max_persist_navigation_count; ++i) {
-    if (ShouldTrackEntry(navigations[i].virtual_url())) {
-      ScheduleCommand(
-          CreateUpdateTabNavigationCommand(kCommandUpdateTabNavigation, tab.id,
-                                           navigations[i]));
-    }
-  }
-}
-
-SessionCommand* TabRestoreService::CreateWindowCommand(SessionID::id_type id,
-                                                       int selected_tab_index,
-                                                       int num_tabs,
-                                                       Time timestamp) {
-  WindowPayload2 payload;
-  // |timestamp| is aligned on a 16 byte boundary, leaving 4 bytes of
-  // uninitialized memory in the struct.
-  memset(&payload, 0, sizeof(payload));
-  payload.window_id = id;
-  payload.selected_tab_index = selected_tab_index;
-  payload.num_tabs = num_tabs;
-  payload.timestamp = timestamp.ToInternalValue();
-
-  SessionCommand* command =
-      new SessionCommand(kCommandWindow, sizeof(payload));
-  memcpy(command->contents(), &payload, sizeof(payload));
-  return command;
-}
+// static
+bool TabRestoreServiceHelper::ValidateEntry(Entry* entry) {
+  if (entry->type == TabRestoreService::TAB)
+    return ValidateTab(static_cast<Tab*>(entry));
 
-SessionCommand* TabRestoreService::CreateSelectedNavigationInTabCommand(
-    SessionID::id_type tab_id,
-    int32 index,
-    Time timestamp) {
-  SelectedNavigationInTabPayload2 payload;
-  payload.id = tab_id;
-  payload.index = index;
-  payload.timestamp = timestamp.ToInternalValue();
-  SessionCommand* command =
-      new SessionCommand(kCommandSelectedNavigationInTab, sizeof(payload));
-  memcpy(command->contents(), &payload, sizeof(payload));
-  return command;
-}
+  if (entry->type == TabRestoreService::WINDOW)
+    return ValidateWindow(static_cast<Window*>(entry));
 
-SessionCommand* TabRestoreService::CreateRestoredEntryCommand(
-    SessionID::id_type entry_id) {
-  RestoredEntryPayload payload = entry_id;
-  SessionCommand* command =
-      new SessionCommand(kCommandRestoredEntry, sizeof(payload));
-  memcpy(command->contents(), &payload, sizeof(payload));
-  return command;
+  NOTREACHED();
+  return false;
 }
 
-int TabRestoreService::GetSelectedNavigationIndexToPersist(const Tab& tab) {
-  const std::vector<TabNavigation>& navigations = tab.navigations;
-  int selected_index = tab.current_navigation_index;
-  int max_index = static_cast<int>(navigations.size());
-
-  // Find the first navigation to persist. We won't persist the selected
-  // navigation if ShouldTrackEntry returns false.
-  while (selected_index >= 0 &&
-         !ShouldTrackEntry(navigations[selected_index].virtual_url())) {
-    selected_index--;
+void TabRestoreServiceHelper::PopulateTab(
+    Tab* tab,
+    int index,
+    TabRestoreServiceDelegate* delegate,
+    NavigationController* controller) {
+  const int pending_index = controller->GetPendingEntryIndex();
+  int entry_count = controller->GetEntryCount();
+  if (entry_count == 0 && pending_index == 0)
+    entry_count++;
+  tab->navigations.resize(static_cast<int>(entry_count));
+  for (int i = 0; i < entry_count; ++i) {
+    NavigationEntry* entry = (i == pending_index) ?
+        controller->GetPendingEntry() : controller->GetEntryAtIndex(i);
+    tab->navigations[i] =
+        TabNavigation::FromNavigationEntry(i, *entry);
   }
+  tab->timestamp = TimeNow();
+  tab->current_navigation_index = controller->GetCurrentEntryIndex();
+  if (tab->current_navigation_index == -1 && entry_count > 0)
+    tab->current_navigation_index = 0;
+  tab->tabstrip_index = index;
 
-  if (selected_index != -1)
-    return selected_index;
-
-  // Couldn't find a navigation to persist going back, go forward.
-  selected_index = tab.current_navigation_index + 1;
-  while (selected_index < max_index &&
-         !ShouldTrackEntry(navigations[selected_index].virtual_url())) {
-    selected_index++;
+  TabContents* tab_contents =
+      TabContents::FromWebContents(controller->GetWebContents());
+  // tab_contents is NULL in some browser tests.
+  if (tab_contents) {
+    const extensions::Extension* extension =
+        extensions::TabHelper::FromWebContents(controller->GetWebContents())->
+            extension_app();
+    if (extension)
+      tab->extension_app_id = extension->id();
   }
 
-  return (selected_index == max_index) ? -1 : selected_index;
-}
-
-void TabRestoreService::OnGotLastSessionCommands(
-    Handle handle,
-    scoped_refptr<InternalGetCommandsRequest> request) {
-  std::vector<Entry*> entries;
-  CreateEntriesFromCommands(request, &entries);
-  // Closed tabs always go to the end.
-  staging_entries_.insert(staging_entries_.end(), entries.begin(),
-                          entries.end());
-  load_state_ |= LOADED_LAST_TABS;
-  LoadStateChanged();
-}
-
-void TabRestoreService::CreateEntriesFromCommands(
-    scoped_refptr<InternalGetCommandsRequest> request,
-    std::vector<Entry*>* loaded_entries) {
-  if (request->canceled() || entries_.size() == kMaxEntries)
-    return;
-
-  std::vector<SessionCommand*>& commands = request->commands;
-  // Iterate through the commands populating entries and id_to_entry.
-  ScopedVector<Entry> entries;
-  IDToEntry id_to_entry;
-  // If non-null we're processing the navigations of this tab.
-  Tab* current_tab = NULL;
-  // If non-null we're processing the tabs of this window.
-  Window* current_window = NULL;
-  // If > 0, we've gotten a window command but not all the tabs yet.
-  int pending_window_tabs = 0;
-  for (std::vector<SessionCommand*>::const_iterator i = commands.begin();
-       i != commands.end(); ++i) {
-    const SessionCommand& command = *(*i);
-    switch (command.id()) {
-      case kCommandRestoredEntry: {
-        if (pending_window_tabs > 0) {
-          // Should never receive a restored command while waiting for all the
-          // tabs in a window.
-          return;
-        }
-
-        current_tab = NULL;
-        current_window = NULL;
-
-        RestoredEntryPayload payload;
-        if (!command.GetPayload(&payload, sizeof(payload)))
-          return;
-        RemoveEntryByID(payload, &id_to_entry, &(entries.get()));
-        break;
-      }
-
-      case kCommandWindow: {
-        WindowPayload2 payload;
-        if (pending_window_tabs > 0) {
-          // Should never receive a window command while waiting for all the
-          // tabs in a window.
-          return;
-        }
-
-        // Try the new payload first
-        if (!command.GetPayload(&payload, sizeof(payload))) {
-          // then the old payload
-          WindowPayload old_payload;
-          if (!command.GetPayload(&old_payload, sizeof(old_payload)))
-            return;
-
-          // Copy the old payload data to the new payload.
-          payload.window_id = old_payload.window_id;
-          payload.selected_tab_index = old_payload.selected_tab_index;
-          payload.num_tabs = old_payload.num_tabs;
-          // Since we don't have a time use time 0 which is used to mark as an
-          // unknown timestamp.
-          payload.timestamp = 0;
-        }
-
-        pending_window_tabs = payload.num_tabs;
-        if (pending_window_tabs <= 0) {
-          // Should always have at least 1 tab. Likely indicates corruption.
-          return;
-        }
-
-        RemoveEntryByID(payload.window_id, &id_to_entry, &(entries.get()));
-
-        current_window = new Window();
-        current_window->selected_tab_index = payload.selected_tab_index;
-        current_window->timestamp = Time::FromInternalValue(payload.timestamp);
-        entries.push_back(current_window);
-        id_to_entry[payload.window_id] = current_window;
-        break;
-      }
-
-      case kCommandSelectedNavigationInTab: {
-        SelectedNavigationInTabPayload2 payload;
-        if (!command.GetPayload(&payload, sizeof(payload))) {
-          SelectedNavigationInTabPayload old_payload;
-          if (!command.GetPayload(&old_payload, sizeof(old_payload)))
-            return;
-          payload.id = old_payload.id;
-          payload.index = old_payload.index;
-          // Since we don't have a time use time 0 which is used to mark as an
-          // unknown timestamp.
-          payload.timestamp = 0;
-        }
-
-        if (pending_window_tabs > 0) {
-          if (!current_window) {
-            // We should have created a window already.
-            NOTREACHED();
-            return;
-          }
-          current_window->tabs.resize(current_window->tabs.size() + 1);
-          current_tab = &(current_window->tabs.back());
-          if (--pending_window_tabs == 0)
-            current_window = NULL;
-        } else {
-          RemoveEntryByID(payload.id, &id_to_entry, &(entries.get()));
-          current_tab = new Tab();
-          id_to_entry[payload.id] = current_tab;
-          current_tab->timestamp = Time::FromInternalValue(payload.timestamp);
-          entries.push_back(current_tab);
-        }
-        current_tab->current_navigation_index = payload.index;
-        break;
-      }
-
-      case kCommandUpdateTabNavigation: {
-        if (!current_tab) {
-          // Should be in a tab when we get this.
-          return;
-        }
-        current_tab->navigations.resize(current_tab->navigations.size() + 1);
-        SessionID::id_type tab_id;
-        if (!RestoreUpdateTabNavigationCommand(
-            command, &current_tab->navigations.back(), &tab_id)) {
-          return;
-        }
-        break;
-      }
-
-      case kCommandPinnedState: {
-        if (!current_tab) {
-          // Should be in a tab when we get this.
-          return;
-        }
-        // NOTE: payload doesn't matter. kCommandPinnedState is only written if
-        // tab is pinned.
-        current_tab->pinned = true;
-        break;
-      }
-
-      case kCommandSetWindowAppName: {
-        if (!current_window) {
-          // We should have created a window already.
-          NOTREACHED();
-          return;
-        }
-
-        SessionID::id_type window_id;
-        std::string app_name;
-        if (!RestoreSetWindowAppNameCommand(command, &window_id, &app_name))
-          return;
-
-        current_window->app_name.swap(app_name);
-        break;
-      }
-
-      case kCommandSetExtensionAppID: {
-        if (!current_tab) {
-          // Should be in a tab when we get this.
-          return;
-        }
-        SessionID::id_type tab_id;
-        std::string extension_app_id;
-        if (!RestoreSetTabExtensionAppIDCommand(command, &tab_id,
-                                                &extension_app_id)) {
-          return;
-        }
-        current_tab->extension_app_id.swap(extension_app_id);
-        break;
-      }
+  tab->user_agent_override =
+      controller->GetWebContents()->GetUserAgentOverride();
 
-      case kCommandSetTabUserAgentOverride: {
-        if (!current_tab) {
-          // Should be in a tab when we get this.
-          return;
-        }
-        SessionID::id_type tab_id;
-        std::string user_agent_override;
-        if (!RestoreSetTabUserAgentOverrideCommand(command, &tab_id,
-                                                   &user_agent_override)) {
-          return;
-        }
-        current_tab->user_agent_override.swap(user_agent_override);
-        break;
-      }
+  // TODO(ajwong): This does not correctly handle storage for isolated apps.
+  tab->session_storage_namespace =
+      controller->GetDefaultSessionStorageNamespace();
 
-      default:
-        // Unknown type, usually indicates corruption of file. Ignore it.
-        return;
-    }
+  // Delegate may be NULL during unit tests.
+  if (delegate) {
+    tab->browser_id = delegate->GetSessionID().id();
+    tab->pinned = delegate->IsTabPinned(tab->tabstrip_index);
   }
-
-  // If there was corruption some of the entries won't be valid.
-  ValidateAndDeleteEmptyEntries(&(entries.get()));
-
-  loaded_entries->swap(entries.get());
 }
 
-TabRestoreServiceDelegate* TabRestoreService::RestoreTab(
+TabRestoreServiceDelegate* TabRestoreServiceHelper::RestoreTab(
     const Tab& tab,
     TabRestoreServiceDelegate* delegate,
     WindowOpenDisposition disposition) {
@@ -1016,7 +446,7 @@ TabRestoreServiceDelegate* TabRestoreService::RestoreTab(
     if (delegate && disposition != NEW_WINDOW) {
       tab_index = tab.tabstrip_index;
     } else {
-      delegate = TabRestoreServiceDelegate::Create(profile(), std::string());
+      delegate = TabRestoreServiceDelegate::Create(profile_, std::string());
       if (tab.has_browser())
         UpdateTabBrowserIDs(tab.browser_id, delegate->GetSessionID().id());
     }
@@ -1040,12 +470,12 @@ TabRestoreServiceDelegate* TabRestoreService::RestoreTab(
         tab.user_agent_override);
     web_contents->GetController().LoadIfNecessary();
   }
-  RecordAppLaunch(profile(), tab);
+  RecordAppLaunch(profile_, tab);
   return delegate;
 }
 
 
-bool TabRestoreService::ValidateTab(Tab* tab) {
+bool TabRestoreServiceHelper::ValidateTab(Tab* tab) {
   if (tab->navigations.empty())
     return false;
 
@@ -1056,7 +486,7 @@ bool TabRestoreService::ValidateTab(Tab* tab) {
   return true;
 }
 
-bool TabRestoreService::ValidateWindow(Window* window) {
+bool TabRestoreServiceHelper::ValidateWindow(Window* window) {
   window->selected_tab_index =
       std::max(0, std::min(window->selected_tab_index,
                            static_cast<int>(window->tabs.size() - 1)));
@@ -1082,18 +512,7 @@ bool TabRestoreService::ValidateWindow(Window* window) {
   return true;
 }
 
-bool TabRestoreService::ValidateEntry(Entry* entry) {
-  if (entry->type == TAB)
-    return ValidateTab(static_cast<Tab*>(entry));
-
-  if (entry->type == WINDOW)
-    return ValidateWindow(static_cast<Window*>(entry));
-
-  NOTREACHED();
-  return false;
-}
-
-bool TabRestoreService::IsTabInteresting(const Tab* tab) {
+bool TabRestoreServiceHelper::IsTabInteresting(const Tab* tab) {
   if (tab->navigations.empty())
     return false;
 
@@ -1105,7 +524,7 @@ bool TabRestoreService::IsTabInteresting(const Tab* tab) {
           GURL(chrome::kChromeUINewTabURL);
 }
 
-bool TabRestoreService::IsWindowInteresting(const Window* window) {
+bool TabRestoreServiceHelper::IsWindowInteresting(const Window* window) {
   if (window->tabs.empty())
     return false;
 
@@ -1115,44 +534,24 @@ bool TabRestoreService::IsWindowInteresting(const Window* window) {
   return IsTabInteresting(&window->tabs[0]);
 }
 
-bool TabRestoreService::FilterEntry(Entry* entry) {
+bool TabRestoreServiceHelper::FilterEntry(Entry* entry) {
   if (!ValidateEntry(entry))
     return false;
 
-  if (entry->type == TAB)
+  if (entry->type == TabRestoreService::TAB)
     return IsTabInteresting(static_cast<Tab*>(entry));
-  else if (entry->type == WINDOW)
+  else if (entry->type == TabRestoreService::WINDOW)
     return IsWindowInteresting(static_cast<Window*>(entry));
 
   NOTREACHED();
   return false;
 }
 
-void TabRestoreService::ValidateAndDeleteEmptyEntries(
-    std::vector<Entry*>* entries) {
-  std::vector<Entry*> valid_entries;
-  std::vector<Entry*> invalid_entries;
-
-  // Iterate from the back so that we keep the most recently closed entries.
-  for (std::vector<Entry*>::reverse_iterator i = entries->rbegin();
-       i != entries->rend(); ++i) {
-    if (ValidateEntry(*i))
-      valid_entries.push_back(*i);
-    else
-      invalid_entries.push_back(*i);
-  }
-  // NOTE: at this point the entries are ordered with newest at the front.
-  entries->swap(valid_entries);
-
-  // Delete the remaining entries.
-  STLDeleteElements(&invalid_entries);
-}
-
-void TabRestoreService::UpdateTabBrowserIDs(SessionID::id_type old_id,
-                                            SessionID::id_type new_id) {
+void TabRestoreServiceHelper::UpdateTabBrowserIDs(SessionID::id_type old_id,
+                                                  SessionID::id_type new_id) {
   for (Entries::iterator i = entries_.begin(); i != entries_.end(); ++i) {
     Entry* entry = *i;
-    if (entry->type == TAB) {
+    if (entry->type == TabRestoreService::TAB) {
       Tab* tab = static_cast<Tab*>(entry);
       if (tab->browser_id == old_id)
         tab->browser_id = new_id;
@@ -1160,103 +559,6 @@ void TabRestoreService::UpdateTabBrowserIDs(SessionID::id_type old_id,
   }
 }
 
-void TabRestoreService::OnGotPreviousSession(
-    Handle handle,
-    std::vector<SessionWindow*>* windows,
-    SessionID::id_type ignored_active_window) {
-  std::vector<Entry*> entries;
-  CreateEntriesFromWindows(windows, &entries);
-  // Previous session tabs go first.
-  staging_entries_.insert(staging_entries_.begin(), entries.begin(),
-                          entries.end());
-  load_state_ |= LOADED_LAST_SESSION;
-  LoadStateChanged();
-}
-
-void TabRestoreService::CreateEntriesFromWindows(
-    std::vector<SessionWindow*>* windows,
-    std::vector<Entry*>* entries) {
-  for (size_t i = 0; i < windows->size(); ++i) {
-    scoped_ptr<Window> window(new Window());
-    if (ConvertSessionWindowToWindow((*windows)[i], window.get()))
-      entries->push_back(window.release());
-  }
-}
-
-bool TabRestoreService::ConvertSessionWindowToWindow(
-    SessionWindow* session_window,
-    Window* window) {
-  for (size_t i = 0; i < session_window->tabs.size(); ++i) {
-    if (!session_window->tabs[i]->navigations.empty()) {
-      window->tabs.resize(window->tabs.size() + 1);
-      Tab& tab = window->tabs.back();
-      tab.pinned = session_window->tabs[i]->pinned;
-      tab.navigations.swap(session_window->tabs[i]->navigations);
-      tab.current_navigation_index =
-          session_window->tabs[i]->current_navigation_index;
-      tab.extension_app_id = session_window->tabs[i]->extension_app_id;
-      tab.timestamp = Time();
-    }
-  }
-  if (window->tabs.empty())
-    return false;
-
-  window->selected_tab_index =
-      std::min(session_window->selected_tab_index,
-               static_cast<int>(window->tabs.size() - 1));
-  window->timestamp = Time();
-  return true;
-}
-
-void TabRestoreService::LoadStateChanged() {
-  if ((load_state_ & (LOADED_LAST_TABS | LOADED_LAST_SESSION)) !=
-      (LOADED_LAST_TABS | LOADED_LAST_SESSION)) {
-    // Still waiting on previous session or previous tabs.
-    return;
-  }
-
-  // We're done loading.
-  load_state_ ^= LOADING;
-
-  if (staging_entries_.empty() || entries_.size() >= kMaxEntries) {
-    STLDeleteElements(&staging_entries_);
-    return;
-  }
-
-  if (staging_entries_.size() + entries_.size() > kMaxEntries) {
-    // If we add all the staged entries we'll end up with more than
-    // kMaxEntries. Delete entries such that we only end up with
-    // at most kMaxEntries.
-    int surplus = kMaxEntries - entries_.size();
-    CHECK_LE(0, surplus);
-    CHECK_GE(static_cast<int>(staging_entries_.size()), surplus);
-    STLDeleteContainerPointers(
-        staging_entries_.begin() + (kMaxEntries - entries_.size()),
-        staging_entries_.end());
-    staging_entries_.erase(
-        staging_entries_.begin() + (kMaxEntries - entries_.size()),
-        staging_entries_.end());
-  }
-
-  // And add them.
-  for (size_t i = 0; i < staging_entries_.size(); ++i) {
-    staging_entries_[i]->from_last_session = true;
-    AddEntry(staging_entries_[i], false, false);
-  }
-
-  // AddEntry takes ownership of the entry, need to clear out entries so that
-  // it doesn't delete them.
-  staging_entries_.clear();
-
-  // Make it so we rewrite all the tabs. We need to do this otherwise we won't
-  // correctly write out the entries when Save is invoked (Save starts from
-  // the front, not the end and we just added the entries to the end).
-  entries_to_write_ = staging_entries_.size();
-
-  PruneEntries();
-  NotifyTabsChanged();
-}
-
-Time TabRestoreService::TimeNow() const {
-  return time_factory_ ? time_factory_->TimeNow() : Time::Now();
+base::Time TabRestoreServiceHelper::TimeNow() const {
+  return time_factory_ ? time_factory_->TimeNow() : base::Time::Now();
 }