backup for dynamic recent tabs submenu

chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc

Index: chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc
diff --git a/chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc b/chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc
index 0ab3291188a7d7226e938272c0ed03b7daf2ff2c..33a24ffd96f6b3d58b3d9236c8ce576ee90154bb 100644
--- a/chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc
+++ b/chrome/browser/ui/toolbar/recent_tabs_sub_menu_model.cc
@@ -41,22 +41,26 @@
 
 namespace {
 
-// First comamnd id for navigatable (and hence executable) tab menu item.
+// First comamnd id for navigatable (and hence executable) tab/window menu item.
 // The models and menu are not 1-1:
-// - menu has "Reopen closed tab", "No tabs from other devices", device section
-//   headers, separators and executable tab items.
-// - |tab_navigation_items_| only has navigatabale/executable tab items.
-// - |window_items_| only has executable open window items.
-// Using an initial command ids for tab/window items makes it easier and less
-// error-prone to manipulate the models and menu.
-// These values must be bigger than the maximum possible number of items in
-// menu, so that index of last menu item doesn't clash with this value when menu
-// items are retrieved via GetIndexOfCommandId.
-const int kFirstTabCommandId = 100;
-const int kFirstWindowCommandId = 200;
-
-// The maximum number of recently closed entries to be shown in the menu.
-const int kMaxRecentlyClosedEntries = 8;
+// - menu has "Recently closed" header, "No tabs from other devices", device
+//   section headers, separators, executable local and foreign tab items, and
+//   executable local window items.
+// - |local_tab_navigation_items_| and |foreign_tab_navigation_items_| only have
+//    navigatabale/executable tab items.
+// - |local_window_items_| only has executable open window items.
+// Using initial command ids for local tab, local window and foreign tab items
+// makes it easier and less error-prone to manipulate the models, data vectors
+// and menu.  These ids must be bigger than the maximum possible number of
+// items in menu, so that index of the last menu item doesn't clash with these
+// values when menu items are retrieved via GetIndexOfCommandId.
+const int kFirstLocalTabCommandId = 100;
+const int kFirstLocalWindowCommandId = 200;
+const int kFirstForeignTabCommandId = 300;
+
+// The maximum number of local recently closed entries (tab or window) to be
+// shown in the menu.
+const int kMaxLocalEntries = 8;
 
 // Comparator function for use with std::sort that will sort sessions by
 // descending modified_time (i.e., most recent first).
@@ -71,43 +75,42 @@ bool SortTabsByRecency(const SessionTab* t1, const SessionTab* t2) {
   return t1->timestamp > t2->timestamp;
 }
 
-// Returns true if the command id is related to a tab model index.
+// Returns true if the command id identifies a tab model index.
 bool IsTabModelCommandId(int command_id) {
-  return command_id >= kFirstTabCommandId && command_id < kFirstWindowCommandId;
+  return command_id >= kFirstForeignTabCommandId ||
+      (command_id >= kFirstLocalTabCommandId &&
+       command_id < kFirstLocalWindowCommandId);
 }
 
-// Returns true if the command id is related to a window model index.
+// Returns true if the command id identifies a window model index.
 bool IsWindowModelCommandId(int command_id) {
-  return command_id >= kFirstWindowCommandId &&
+  return command_id >= kFirstLocalWindowCommandId &&
          command_id < RecentTabsSubMenuModel::kRecentlyClosedHeaderCommandId;
 }
 
-// Convert |tab_model_index| to command id of menu item.
-int TabModelIndexToCommandId(int tab_model_index) {
-  int command_id = tab_model_index + kFirstTabCommandId;
-  DCHECK_LT(command_id, kFirstWindowCommandId);
+// Convert |tab_model_index| to command id of menu item, with |first_command_id|
+// as the base command id.
+int TabModelIndexToCommandId(int tab_model_index, int first_command_id) {
+  int command_id = tab_model_index + first_command_id;
+  DCHECK(first_command_id == kFirstForeignTabCommandId ||
+         command_id < kFirstLocalWindowCommandId);
   return command_id;
 }
 
-// Convert |command_id| of menu item to index in tab model.
-int CommandIdToTabModelIndex(int command_id) {
-  DCHECK_GE(command_id, kFirstTabCommandId);
-  DCHECK_LT(command_id, kFirstWindowCommandId);
-  return command_id - kFirstTabCommandId;
-}
-
 // Convert |window_model_index| to command id of menu item.
 int WindowModelIndexToCommandId(int window_model_index) {
-  int command_id = window_model_index + kFirstWindowCommandId;
+  int command_id = window_model_index + kFirstLocalWindowCommandId;
+  DCHECK_LT(command_id, kFirstForeignTabCommandId);
   DCHECK_LT(command_id, RecentTabsSubMenuModel::kRecentlyClosedHeaderCommandId);
   return command_id;
 }
 
 // Convert |command_id| of menu item to index in window model.
 int CommandIdToWindowModelIndex(int command_id) {
-  DCHECK_GE(command_id, kFirstWindowCommandId);
+  DCHECK_GE(command_id, kFirstLocalWindowCommandId);
+  DCHECK_LT(command_id, kFirstForeignTabCommandId);
   DCHECK_LT(command_id, RecentTabsSubMenuModel::kRecentlyClosedHeaderCommandId);
-  return command_id - kFirstWindowCommandId;
+  return command_id - kFirstLocalWindowCommandId;
 }
 
 }  // namespace
@@ -120,7 +123,8 @@ enum RecentTabAction {
   LIMIT_RECENT_TAB_ACTION
 };
 
-// An element in |RecentTabsSubMenuModel::tab_navigation_items_| that stores
+// An element in |RecentTabsSubMenuModel::local_tab_navigation_items_| or
+// |RecentTabsSubMenuModel::foreign_tab_navigation_items_| that stores
 // the navigation information of a local or foreign tab required to restore the
 // tab.
 struct RecentTabsSubMenuModel::TabNavigationItem {
@@ -157,9 +161,26 @@ RecentTabsSubMenuModel::RecentTabsSubMenuModel(
     : ui::SimpleMenuModel(this),
       browser_(browser),
       associator_(associator),
+      last_local_model_index_(-1),
       default_favicon_(ResourceBundle::GetSharedInstance().
           GetNativeImageNamed(IDR_DEFAULT_FAVICON)),
       weak_ptr_factory_(this) {
+  // Invoke asynchronous call to load tabs from local last session, which does
+  // nothing if the tabs have already been loaded or they shouldn't be loaded.
+  // TabRestoreServiceChanged() will be called after the tabs are loaded.
+  TabRestoreService* service =
+      TabRestoreServiceFactory::GetForProfile(browser_->profile());
+  if (service) {
+    service->LoadTabsFromLastSession();
+
+// TODO(sail): enable this when mac implements the dynamic menu, together with
+// MenuModelDelegate::PrepareChange, OnItemRemoved, OnItemAdded and ChangesDone.
+#if !defined(OS_MACOSX)
+    service->AddObserver(this);
+#endif
+  }
+
+  // Build the menu.
   Build();
 
   // Retrieve accelerator key for IDC_RESTORE_TAB now, because on ASH, it's not
@@ -183,6 +204,29 @@ RecentTabsSubMenuModel::RecentTabsSubMenuModel(
 }
 
 RecentTabsSubMenuModel::~RecentTabsSubMenuModel() {
+  TabRestoreService* service =
+      TabRestoreServiceFactory::GetForProfile(browser_->profile());
+  if (service)
+    service->RemoveObserver(this);
+}
+
+int RecentTabsSubMenuModel::ModelIndexToIdInParentMenu(int model_index) const {
+  // If |model_index| identifies a local tab/window menu item, return as is;
+  // otherwise, reserve enough id's for maximum possible local entries.
+  if (model_index <= last_local_model_index_)
+    return model_index;
+  return model_index + kMaxLocalEntries - last_local_model_index_;
+}
+
+int RecentTabsSubMenuModel::IdInParentMenuToModelIndex(
+    int id_in_parent_menu) const {
+  // If |id_in_parent_menu| identifies a local tab/window menu item, return as
+  // is; otherwise, ModelIndexToIdInParentMenu() would have reserved enough Id's
+  // for maximum possible local entries, so reverse that logic.
+  int index = id_in_parent_menu <= last_local_model_index_ ? id_in_parent_menu :
+      id_in_parent_menu - kMaxLocalEntries + last_local_model_index_;
+  DCHECK(index >= 0 && index < GetItemCount());
+  return index;
 }
 
 bool RecentTabsSubMenuModel::IsCommandIdChecked(int command_id) const {
@@ -238,10 +282,9 @@ void RecentTabsSubMenuModel::ExecuteCommand(int command_id, int event_flags) {
       TabRestoreServiceDelegate::FindDelegateForWebContents(
           browser_->tab_strip_model()->GetActiveWebContents());
   if (IsTabModelCommandId(command_id)) {
-    int model_idx = CommandIdToTabModelIndex(command_id);
-    DCHECK(model_idx >= 0 &&
-           model_idx < static_cast<int>(tab_navigation_items_.size()));
-    const TabNavigationItem& item = tab_navigation_items_[model_idx];
+    TabNavigationItems* tab_items = NULL;
+    int model_idx = CommandIdToTabModelIndex(command_id, &tab_items);
+    const TabNavigationItem& item = tab_items->at(model_idx);
     DCHECK(item.tab_id > -1 && item.url.is_valid());
 
     if (item.session_tag.empty()) {  // Restore tab of local session.
@@ -271,10 +314,10 @@ void RecentTabsSubMenuModel::ExecuteCommand(int command_id, int event_flags) {
     if (service && delegate) {
       int model_idx = CommandIdToWindowModelIndex(command_id);
       DCHECK(model_idx >= 0 &&
-             model_idx < static_cast<int>(window_items_.size()));
+             model_idx < static_cast<int>(local_window_items_.size()));
       UMA_HISTOGRAM_ENUMERATION("WrenchMenu.RecentTabsSubMenu", RESTORE_WINDOW,
                                 LIMIT_RECENT_TAB_ACTION);
-      service->RestoreEntryById(delegate, window_items_[model_idx],
+      service->RestoreEntryById(delegate, local_window_items_[model_idx],
                                 browser_->host_desktop_type(), disposition);
     }
   }
@@ -300,17 +343,15 @@ int RecentTabsSubMenuModel::GetMaxWidthForItemAtIndex(int item_index) const {
   return 320;
 }
 
-bool RecentTabsSubMenuModel::GetURLAndTitleForItemAtIndex(
-    int index,
-    std::string* url,
-    string16* title) const {
+bool RecentTabsSubMenuModel::GetURLAndTitleForItemAtIndex(int index,
+                                                          std::string* url,
+                                                          string16* title) {
   int command_id = GetCommandIdAt(index);
   if (IsTabModelCommandId(command_id)) {
-    int model_idx = CommandIdToTabModelIndex(command_id);
-    DCHECK(model_idx >= 0 &&
-           model_idx < static_cast<int>(tab_navigation_items_.size()));
-    *url = tab_navigation_items_[model_idx].url.possibly_invalid_spec();
-    *title = tab_navigation_items_[model_idx].title;
+    TabNavigationItems* tab_items = NULL;
+    int model_idx = CommandIdToTabModelIndex(command_id, &tab_items);
+    *url = tab_items->at(model_idx).url.possibly_invalid_spec();
+    *title = tab_items->at(model_idx).title;
     return true;
   }
   return false;
@@ -318,66 +359,81 @@ bool RecentTabsSubMenuModel::GetURLAndTitleForItemAtIndex(
 
 void RecentTabsSubMenuModel::Build() {
   // The menu contains:
-  // - Recently closed tabs header, then list of tabs, then separator
+  // - Recently closed header, then list of local recently closed tabs/windows,
+  //   then separator
   // - device 1 section header, then list of tabs from device, then separator
   // - device 2 section header, then list of tabs from device, then separator
   // - device 3 section header, then list of tabs from device, then separator
   // - More... to open the history tab to get more other devices.
-  // |tab_navigation_items_| only contains navigatable (and hence executable)
-  // tab items for other devices, and |window_items_| contains the recently
-  // closed windows.
-  BuildRecentTabs();
-  BuildDevices();
+  // |local_tab_navigation_items_| and |foreign_tab_navigation_items_| only
+  // contain navigatable (and hence executable) tab items for local recently
+  // closed tabs and tabs of other devices respectively.
+  // |local_window_items_| contains the local recently closed windows.
+  BuildLocalEntries();
+  BuildForeignTabs();
 }
 
-void RecentTabsSubMenuModel::BuildRecentTabs() {
-  ListValue recently_closed_list;
+void RecentTabsSubMenuModel::BuildLocalEntries() {
+  // All local items use InsertItem*At() to append or insert a menu item.
+  // We're appending if building the entries for the first time i.e. invoked
+  // from Constructor(), inserting when local entries change subsequently i.e.
+  // invoked from TabRestoreServiceChanged().
+
+  int curr_model_index = 0;
+
   TabRestoreService* service =
       TabRestoreServiceFactory::GetForProfile(browser_->profile());
-  if (service) {
-    // This does nothing if the tabs have already been loaded or they
-    // shouldn't be loaded.
-    service->LoadTabsFromLastSession();
-  }
-
   if (!service || service->entries().size() == 0) {
     // This is to show a disabled restore tab entry with the accelerator to
     // teach users about this command.
-    AddItemWithStringId(kDisabledRecentlyClosedHeaderCommandId,
-                        IDS_NEW_TAB_RECENTLY_CLOSED);
-    return;
-  }
-
-  AddItemWithStringId(kRecentlyClosedHeaderCommandId,
-                      IDS_NEW_TAB_RECENTLY_CLOSED);
-  ResourceBundle& rb = ResourceBundle::GetSharedInstance();
-  SetIcon(GetItemCount() - 1,
-          rb.GetNativeImageNamed(IDR_RECENTLY_CLOSED_WINDOW));
-
-  int added_count = 0;
-  TabRestoreService::Entries entries = service->entries();
-  for (TabRestoreService::Entries::const_iterator it = entries.begin();
-       it != entries.end() && added_count < kMaxRecentlyClosedEntries; ++it) {
-    TabRestoreService::Entry* entry = *it;
-    if (entry->type == TabRestoreService::TAB) {
-      TabRestoreService::Tab* tab = static_cast<TabRestoreService::Tab*>(entry);
-      const sessions::SerializedNavigationEntry& current_navigation =
-          tab->navigations.at(tab->current_navigation_index);
-      BuildLocalTabItem(
-          entry->id,
-          current_navigation.title(),
-          current_navigation.virtual_url());
-    } else  {
-      DCHECK_EQ(entry->type, TabRestoreService::WINDOW);
-      BuildWindowItem(
-          entry->id,
-          static_cast<TabRestoreService::Window*>(entry)->tabs.size());
+    InsertItemWithStringIdAt(curr_model_index++,
+                             kDisabledRecentlyClosedHeaderCommandId,
+                             IDS_NEW_TAB_RECENTLY_CLOSED);
+  } else {
+    InsertItemWithStringIdAt(curr_model_index,
+                             kRecentlyClosedHeaderCommandId,
+                             IDS_NEW_TAB_RECENTLY_CLOSED);
+    ResourceBundle& rb = ResourceBundle::GetSharedInstance();
+    SetIcon(curr_model_index,
+            rb.GetNativeImageNamed(IDR_RECENTLY_CLOSED_WINDOW));
+    ++curr_model_index;
+
+    int added_count = 0;
+    TabRestoreService::Entries entries = service->entries();
+    for (TabRestoreService::Entries::const_iterator it = entries.begin();
+         it != entries.end() && added_count < kMaxLocalEntries; ++it) {
+      TabRestoreService::Entry* entry = *it;
+      if (entry->type == TabRestoreService::TAB) {
+        TabRestoreService::Tab* tab =
+            static_cast<TabRestoreService::Tab*>(entry);
+        const sessions::SerializedNavigationEntry& current_navigation =
+            tab->navigations.at(tab->current_navigation_index);
+        BuildLocalTabItem(
+            entry->id,
+            current_navigation.title(),
+            current_navigation.virtual_url(),
+            curr_model_index);
+      } else  {
+        DCHECK_EQ(entry->type, TabRestoreService::WINDOW);
+        BuildLocalWindowItem(
+            entry->id,
+            static_cast<TabRestoreService::Window*>(entry)->tabs.size(),
+            curr_model_index);
+      }
+      ++added_count;
+      ++curr_model_index;
     }
-    ++added_count;
   }
+
+  DCHECK_GT(curr_model_index, 0);
+  last_local_model_index_ = curr_model_index - 1;
 }
 
-void RecentTabsSubMenuModel::BuildDevices() {
+void RecentTabsSubMenuModel::BuildForeignTabs() {
+  // All foreign items (device headers or tabs) use AddItem*() to append a menu
+  // item, because they are always only built once (i.e. invoked from
+  // Constructor()) and don't change after that.
+
   browser_sync::SessionModelAssociator* associator = GetModelAssociator();
   std::vector<const browser_sync::SyncedSession*> sessions;
   if (!associator || !associator->GetAllForeignSessions(&sessions)) {
@@ -451,50 +507,56 @@ void RecentTabsSubMenuModel::BuildDevices() {
   AddItemWithStringId(IDC_SHOW_HISTORY, IDS_RECENT_TABS_MORE);
 }
 
-void RecentTabsSubMenuModel::BuildLocalTabItem(
-    int session_id,
-    const string16& title,
-    const GURL& url) {
+void RecentTabsSubMenuModel::BuildLocalTabItem(int session_id,
+                                               const string16& title,
+                                               const GURL& url,
+                                               int curr_model_index) {
   TabNavigationItem item("", session_id, title, url);
-  int command_id = TabModelIndexToCommandId(tab_navigation_items_.size());
+  int command_id = TabModelIndexToCommandId(
+      local_tab_navigation_items_.size(), kFirstLocalTabCommandId);
+  // See comments in BuildLocalEntries() about usage of InsertItem*At().
   // There may be no tab title, in which case, use the url as tab title.
-  AddItem(command_id, title.empty() ? UTF8ToUTF16(item.url.spec()) : title);
-  AddTabFavicon(tab_navigation_items_.size(), command_id, item.url);
-  tab_navigation_items_.push_back(item);
+  InsertItemAt(curr_model_index, command_id,
+               title.empty() ? UTF8ToUTF16(item.url.spec()) : title);
+  AddTabFavicon(command_id, item.url);
+  local_tab_navigation_items_.push_back(item);
 }
 
-void RecentTabsSubMenuModel::BuildForeignTabItem(
-    const std::string& session_tag,
-    const SessionTab& tab) {
+void RecentTabsSubMenuModel::BuildLocalWindowItem(
+    const SessionID::id_type& window_id,
+    int num_tabs,
+    int curr_model_index) {
+  int command_id = WindowModelIndexToCommandId(local_window_items_.size());
+  // See comments in BuildLocalEntries() about usage of InsertItem*At().
+  if (num_tabs == 1) {
+    InsertItemWithStringIdAt(curr_model_index, command_id,
+                             IDS_NEW_TAB_RECENTLY_CLOSED_WINDOW_SINGLE);
+  } else {
+    InsertItemAt(curr_model_index, command_id, l10n_util::GetStringFUTF16(
+        IDS_NEW_TAB_RECENTLY_CLOSED_WINDOW_MULTIPLE,
+        base::IntToString16(num_tabs)));
+  }
+  ResourceBundle& rb = ResourceBundle::GetSharedInstance();
+  SetIcon(curr_model_index, rb.GetNativeImageNamed(IDR_RECENTLY_CLOSED_WINDOW));
+  local_window_items_.push_back(window_id);
+}
+
+void RecentTabsSubMenuModel::BuildForeignTabItem(const std::string& session_tag,
+                                                 const SessionTab& tab) {
   const sessions::SerializedNavigationEntry& current_navigation =
       tab.navigations.at(tab.normalized_navigation_index());
   TabNavigationItem item(session_tag, tab.tab_id.id(),
                          current_navigation.title(),
                          current_navigation.virtual_url());
-  int command_id = TabModelIndexToCommandId(tab_navigation_items_.size());
+  int command_id = TabModelIndexToCommandId(
+      foreign_tab_navigation_items_.size(), kFirstForeignTabCommandId);
+  // See comments in BuildForeignTabs() about usage of AddItem*().
   // There may be no tab title, in which case, use the url as tab title.
   AddItem(command_id,
           current_navigation.title().empty() ?
               UTF8ToUTF16(item.url.spec()) : current_navigation.title());
-  AddTabFavicon(tab_navigation_items_.size(), command_id, item.url);
-  tab_navigation_items_.push_back(item);
-}
-
-void RecentTabsSubMenuModel::BuildWindowItem(
-    const SessionID::id_type& window_id,
-    int num_tabs) {
-  int command_id = WindowModelIndexToCommandId(window_items_.size());
-  if (num_tabs == 1) {
-    AddItemWithStringId(command_id, IDS_NEW_TAB_RECENTLY_CLOSED_WINDOW_SINGLE);
-  } else {
-    AddItem(command_id, l10n_util::GetStringFUTF16(
-        IDS_NEW_TAB_RECENTLY_CLOSED_WINDOW_MULTIPLE,
-        base::IntToString16(num_tabs)));
-  }
-  ResourceBundle& rb = ResourceBundle::GetSharedInstance();
-  SetIcon(GetItemCount() - 1,
-          rb.GetNativeImageNamed(IDR_RECENTLY_CLOSED_WINDOW));
-  window_items_.push_back(window_id);
+  AddTabFavicon(command_id, item.url);
+  foreign_tab_navigation_items_.push_back(item);
 }
 
 void RecentTabsSubMenuModel::AddDeviceFavicon(
@@ -524,9 +586,7 @@ void RecentTabsSubMenuModel::AddDeviceFavicon(
   SetIcon(index_in_menu, rb.GetNativeImageNamed(favicon_id));
 }
 
-void RecentTabsSubMenuModel::AddTabFavicon(int model_index,
-                                           int command_id,
-                                           const GURL& url) {
+void RecentTabsSubMenuModel::AddTabFavicon(int command_id, const GURL& url) {
   int index_in_menu = GetIndexOfCommandId(command_id);
 
   // If tab has synced favicon, use it.
@@ -537,9 +597,8 @@ void RecentTabsSubMenuModel::AddTabFavicon(int model_index,
   scoped_refptr<base::RefCountedMemory> favicon_png;
   if (associator &&
       associator->GetSyncedFaviconForPageURL(url.spec(), &favicon_png)) {
-    gfx::Image image = gfx::Image::CreateFrom1xPNGBytes(
-        favicon_png->front(),
-        favicon_png->size());
+    gfx::Image image = gfx::Image::CreateFrom1xPNGBytes(favicon_png->front(),
+                                                        favicon_png->size());
     SetIcon(index_in_menu, image);
     return;
   }
@@ -561,7 +620,9 @@ void RecentTabsSubMenuModel::AddTabFavicon(int model_index,
       base::Bind(&RecentTabsSubMenuModel::OnFaviconDataAvailable,
                  weak_ptr_factory_.GetWeakPtr(),
                  command_id),
-      &cancelable_task_tracker_);
+      command_id >= kFirstForeignTabCommandId ?
+          &foreign_tab_cancelable_task_tracker_ :
+          &local_tab_cancelable_task_tracker_);
 }
 
 void RecentTabsSubMenuModel::OnFaviconDataAvailable(
@@ -569,14 +630,41 @@ void RecentTabsSubMenuModel::OnFaviconDataAvailable(
     const chrome::FaviconImageResult& image_result) {
   if (image_result.image.IsEmpty())
     return;
-  DCHECK(!tab_navigation_items_.empty());
   int index_in_menu = GetIndexOfCommandId(command_id);
-  DCHECK(index_in_menu != -1);
+  DCHECK_GT(index_in_menu, -1);
   SetIcon(index_in_menu, image_result.image);
   if (GetMenuModelDelegate())
     GetMenuModelDelegate()->OnIconChanged(index_in_menu);
 }
 
+int RecentTabsSubMenuModel::CommandIdToTabModelIndex(
+    int command_id, TabNavigationItems** tab_items) {
+  if (command_id >= kFirstForeignTabCommandId) {
+    *tab_items = &foreign_tab_navigation_items_;
+    return command_id - kFirstForeignTabCommandId;
+  }
+  DCHECK_GE(command_id, kFirstLocalTabCommandId);
+  DCHECK_LT(command_id, kFirstLocalWindowCommandId);
+  *tab_items = &local_tab_navigation_items_;
+  return command_id - kFirstLocalTabCommandId;
+}
+
+void RecentTabsSubMenuModel::ClearLocalEntries() {
+  // Remove local items (recent tabs and windows) from model.
+  while (last_local_model_index_ >= 0)
+    RemoveItemAt(last_local_model_index_--);
+
+  // Cancel asynchronous FaviconService::GetFaviconImageForURL() tasks of all
+  // local tabs.
+  local_tab_cancelable_task_tracker_.TryCancelAll();
+
+  // Remove all local tab navigation items.
+  local_tab_navigation_items_.clear();
+
+  // Remove all local window items.
+  local_window_items_.clear();
+}
+
 browser_sync::SessionModelAssociator*
     RecentTabsSubMenuModel::GetModelAssociator() {
   if (!associator_) {
@@ -588,3 +676,33 @@ browser_sync::SessionModelAssociator*
   }
   return associator_;
 }
+
+void RecentTabsSubMenuModel::TabRestoreServiceChanged(
+    TabRestoreService* service) {
+  ui::MenuModelDelegate* menu_model_delegate = GetMenuModelDelegate();
+  if (menu_model_delegate) {
+    menu_model_delegate->PrepareForChange();
+
+    // Notify delegate to remove all local entries from the menu; do so in
+    // decreasing order so that indexes of remaining items don't change.
+    for (int i = last_local_model_index_; i >=0; --i)
+      menu_model_delegate->OnItemRemoved(i);
+  }
+
+  ClearLocalEntries();
+
+  BuildLocalEntries();
+
+  if (menu_model_delegate) {
+    // Notify delegate to add the new local entries to the menu.
+    for (int i = 0; i <= last_local_model_index_; ++i)
+      menu_model_delegate->OnItemAdded(i);
+
+    menu_model_delegate->ChangesDone();
+  }
+}
+
+void RecentTabsSubMenuModel::TabRestoreServiceDestroyed(
+    TabRestoreService* service) {
+  TabRestoreServiceChanged(service);
+}