Revert of Track task ids for navigations cross multiple tabs.

components/sync_sessions/task_tracker.h

 // Copyright 2017 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.
 
 #ifndef COMPONENTS_SYNC_SESSIONS_TASK_TRACKER_H_
 #define COMPONENTS_SYNC_SESSIONS_TASK_TRACKER_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 11 matching lines @@
 namespace sync_sessions {
 
 // Class to generate and manage task ids for navigations of a tab. For each
 // current navigation of a tab, UpdateWithNavigation(int navigation_index,
 //            ui::PageTransition transition)
 // needs to be called to update the object.
 //
 // TODO(shenchao): If the tab is restored, then the input navigation is not
 // necessarily the first navigation in this case. Need to fix it by initalizing
 // the object with restored data.
+// TODO(shenchao): Support to track tasks cross tabs.
 class TabTasks {
  public:
   TabTasks();
-  explicit TabTasks(const TabTasks* source_tab);
   virtual ~TabTasks();
 
   // Gets top-down task id list of ancestors and itself for
   // |navigation_index|-th navigation of the tab.
   std::vector<int64_t> GetTaskIdsForNavigation(int navigation_index) const;
 
   int GetNavigationsCount() const;
 
   // Updates the current task of the tab, given current navigation index of the
   // tab as |navigation_index|, and its |transition|.
@@ skipping 11 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(TaskTrackerTest,
                            CreateSubTaskFromExcludedAncestorTask);
 
   struct TaskIdAndRoot {
     // Root task index in task_ids_. Negative value means it's an invalid task
     // just for filling the task_ids_.
     int root_navigation_index;
     int64_t task_id;
   };
 
-  // Get position within task_ids_ for the navigation at |navigation_index| of
-  // the tab.
-  int GetTaskIdPositionFromNavigationIndex(int navigation_index) const;
-
-  // Get index of corresponding navigation of the tab at |task_id_position|
-  // within task_ids_.
-  int GetNavigationIndexFromTaskIdPosition(int task_id_position) const;
-
   // Task ids (with root task) for the navigations of the tab. The vector is
   // corresponding to the sequence of navigations of the tab.
   std::vector<TaskIdAndRoot> task_ids_;
   // Index of current navigation in task_ids_.
   int current_navigation_index_ = -1;
   // Number of oldest ancestors which have been excluded from being tracked in
   // task_ids_;
   int excluded_navigation_num_ = 0;
-  // Number of tasks from source tab.
-  int source_tab_task_num_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(TabTasks);
 };
 
 // Tracks tasks of current session.
 class TaskTracker {
  public:
   // Constructs with a clock to get timestamp as new task ids.
   TaskTracker();
   virtual ~TaskTracker();
 
   // Returns a TabTasks pointer, which is owned by this object, for the tab of
   // given |tab_id|.
   TabTasks* GetTabTasks(SessionID::id_type tab_id);
 
-  // Returns a TabTasks pointer, which is owned by this object, for the tab of
-  // given |tab_id|, which is created from a source tab |source_tab_id|.
-  TabTasks* GetTabTasks(SessionID::id_type tab_id,
-                        SessionID::id_type source_tab_id);
-
   // Cleans tracked task ids of navigations in the tab of |tab_id|.
   void CleanTabTasks(SessionID::id_type tab_id);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(TaskTrackerTest, CleanTabTasks);
   std::map<SessionID::id_type, std::unique_ptr<TabTasks>> local_tab_tasks_map_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskTracker);
 };
 
 }  // namespace sync_sessions
 
 #endif  // COMPONENTS_SYNC_SESSIONS_TASK_TRACKER_H_