[Sync] Restore previous session if no tabbed windows present

chrome/browser/ui/sync/tab_contents_synced_tab_delegate.cc

 // 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.
 
 #include "chrome/browser/ui/sync/tab_contents_synced_tab_delegate.h"
 
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sessions/session_tab_helper.h"
 #include "chrome/browser/sync/sessions/sync_sessions_router_tab_helper.h"
 #include "chrome/common/features.h"
 #include "components/sessions/content/content_serialized_navigation_builder.h"
 #include "components/sync_sessions/sync_sessions_client.h"
 #include "components/sync_sessions/synced_window_delegate.h"
 #include "components/sync_sessions/synced_window_delegates_getter.h"
+#include "components/sync_sessions/tab_node_pool.h"
 #include "content/public/browser/favicon_status.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/features/features.h"
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "chrome/browser/extensions/tab_helper.h"
 #include "extensions/common/extension.h"
 #endif
@@ skipping 15 matching lines @@
   int pending_index = web_contents->GetController().GetPendingEntryIndex();
   return (pending_index == i)
              ? web_contents->GetController().GetPendingEntry()
              : web_contents->GetController().GetEntryAtIndex(i);
 }
 
 }  // namespace
 
 TabContentsSyncedTabDelegate::TabContentsSyncedTabDelegate(
     content::WebContents* web_contents)
-    : web_contents_(web_contents), sync_session_id_(0) {}
+    : web_contents_(web_contents),
+      sync_session_id_(sync_sessions::TabNodePool::kInvalidTabNodeID) {}
 
 TabContentsSyncedTabDelegate::~TabContentsSyncedTabDelegate() {}
 
 SessionID::id_type TabContentsSyncedTabDelegate::GetWindowId() const {
   return SessionTabHelper::FromWebContents(web_contents_)->window_id().id();
 }
 
 SessionID::id_type TabContentsSyncedTabDelegate::GetSessionId() const {
   return SessionTabHelper::FromWebContents(web_contents_)->session_id().id();
 }
@@ skipping 110 matching lines @@
   }
   return false;
 }
 
 SessionID::id_type TabContentsSyncedTabDelegate::GetSourceTabID() const {
   sync_sessions::SyncSessionsRouterTabHelper* helper =
       sync_sessions::SyncSessionsRouterTabHelper::FromWebContents(
           web_contents_);
   return helper->source_tab_id();
 }