[MD Bookmarks] Fix singleton tab behavior.

components/bookmarks/browser/bookmark_model.cc

 // Copyright 2014 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.
 
 #include "components/bookmarks/browser/bookmark_model.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
@@ skipping 92 matching lines @@
                              int index,
                              std::unique_ptr<BookmarkNode> node) override {}
 
   DISALLOW_COPY_AND_ASSIGN(EmptyUndoDelegate);
 };
 
 }  // namespace
 
 // BookmarkModel --------------------------------------------------------------
 
+const int64_t BookmarkModel::BOOKMARKS_BAR_NODE_ID = 1;

[sky, 2017/05/25 18:07:05]

Rather than exposing these, how about using bookmark_bar_node()->id()?

[calamity, 2017/05/26 03:33:34]

Done.

+const int64_t BookmarkModel::OTHER_BOOKMARKS_NODE_ID = 2;
+const int64_t BookmarkModel::MOBILE_BOOKMARKS_NODE_ID = 3;
+
 BookmarkModel::BookmarkModel(std::unique_ptr<BookmarkClient> client)
     : client_(std::move(client)),
       loaded_(false),
       root_(GURL()),
       bookmark_bar_node_(NULL),
       other_node_(NULL),
       mobile_node_(NULL),
       next_node_id_(1),
       observers_(
           base::ObserverList<BookmarkModelObserver>::NOTIFY_EXISTING_ONLY),
@@ skipping 893 matching lines @@
          type == BookmarkNode::OTHER_NODE ||
          type == BookmarkNode::MOBILE);
   BookmarkPermanentNode* node =
       new BookmarkPermanentNode(generate_next_node_id());
   node->set_type(type);
   node->set_visible(client_->IsPermanentNodeVisible(node));
 
   int title_id;
   switch (type) {
     case BookmarkNode::BOOKMARK_BAR:
+      DCHECK_EQ(BOOKMARKS_BAR_NODE_ID, node->id());
       title_id = IDS_BOOKMARK_BAR_FOLDER_NAME;
       break;
     case BookmarkNode::OTHER_NODE:
+      DCHECK_EQ(OTHER_BOOKMARKS_NODE_ID, node->id());
       title_id = IDS_BOOKMARK_BAR_OTHER_FOLDER_NAME;
       break;
     case BookmarkNode::MOBILE:
+      DCHECK_EQ(MOBILE_BOOKMARKS_NODE_ID, node->id());
       title_id = IDS_BOOKMARK_BAR_MOBILE_FOLDER_NAME;
       break;
     default:
       NOTREACHED();
       title_id = IDS_BOOKMARK_BAR_FOLDER_NAME;
       break;
   }
   node->SetTitle(l10n_util::GetStringUTF16(title_id));
   return node;
 }
@@ skipping 81 matching lines @@
   undo_delegate_ = undo_delegate;
   if (undo_delegate_)
     undo_delegate_->SetUndoProvider(this);
 }
 
 BookmarkUndoDelegate* BookmarkModel::undo_delegate() const {
   return undo_delegate_ ? undo_delegate_ : empty_undo_delegate_.get();
 }
 
 }  // namespace bookmarks