Revert of Track task ids for navigations cross multiple tabs.

components/sync_sessions/sessions_sync_manager.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/sync_sessions/sessions_sync_manager.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/format_macros.h"
@@ skipping 481 matching lines @@
     SyncedTabDelegate* const tab_delegate,
     sync_pb::SessionSpecifics* session_specifics) {
   sync_pb::SessionTab* tab_specifics = session_specifics->mutable_tab();
   // Index in the whole navigations of the tab.
   int current_navigation_index = tab_delegate->GetCurrentEntryIndex();
   // Index in the tab_specifics, where the navigations is a -6/+6 window
   int current_index_in_tab_specifics =
       tab_specifics->current_navigation_index();
   int64_t current_navigation_global_id =
       tab_specifics->navigation(current_index_in_tab_specifics).global_id();
-  SessionID::id_type source_tab_id = tab_delegate->GetSourceTabID();
 
   TabTasks* tab_tasks =
-      source_tab_id == kInvalidTabID
-          ? task_tracker_->GetTabTasks(tab_delegate->GetSessionId())
-          : task_tracker_->GetTabTasks(tab_delegate->GetSessionId(),
-                                       source_tab_id);
+      task_tracker_->GetTabTasks(tab_delegate->GetSessionId());
   tab_tasks->UpdateWithNavigation(
       current_navigation_index,
       tab_delegate->GetTransitionAtIndex(current_navigation_index),
       current_navigation_global_id);
 
   for (int i = 0; i < tab_specifics->navigation_size(); i++) {
     // Excluding blocked navigations, which are appended at tail.
     if (tab_specifics->navigation(i).blocked_state() ==
         sync_pb::TabNavigation::STATE_BLOCKED) {
       break;
@@ skipping 775 matching lines @@
 }
 
 // static
 std::string SessionsSyncManager::TagHashFromSpecifics(
     const sync_pb::SessionSpecifics& specifics) {
   return syncer::GenerateSyncableHash(syncer::SESSIONS,
                                       TagFromSpecifics(specifics));
 }
 
 };  // namespace sync_sessions