Revert of Track task ids for navigations cross multiple tabs.

components/sync_sessions/task_tracker.cc

 // 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.
 
 #include "components/sync_sessions/task_tracker.h"
 
 #include <utility>
 
 #include "base/numerics/safe_conversions.h"
 
 namespace sync_sessions {
 
 namespace {
 // The maximum number of tasks we track in a tab.
 int kMaxNumTasksPerTab = 100;
 }
 
 TabTasks::TabTasks() {}
 
-TabTasks::TabTasks(const TabTasks* source_tab) {
-  if (source_tab->current_navigation_index_ >= 0) {
-    std::vector<int64_t> source_tab_task_ids =
-        source_tab->GetTaskIdsForNavigation(
-            source_tab->current_navigation_index_);
-    for (auto source_tab_task_id : source_tab_task_ids)
-      task_ids_.push_back({0, source_tab_task_id});
-
-    source_tab_task_num_ = source_tab_task_ids.size();
-  }
-}
-
 TabTasks::~TabTasks() {}
 
 std::vector<int64_t> TabTasks::GetTaskIdsForNavigation(
     int navigation_index) const {
   CHECK_LE(0, navigation_index);
   CHECK_LT(navigation_index, GetNavigationsCount());
 
   std::vector<int64_t> root_to_self_task_ids;
   // Position of the navigation in task_ids_ vector.
-  int navigation_position =
-      GetTaskIdPositionFromNavigationIndex(navigation_index);
+  int navigation_position = navigation_index - excluded_navigation_num_;
 
   // If navigation_index is an excluded ancestor task, returns empty.
   if (navigation_position < 0)
     return root_to_self_task_ids;
 
   TaskIdAndRoot task_id_and_root = task_ids_[navigation_position];
 
   // If navigation_index is an invalid task, returns empty.
   if (task_id_and_root.root_navigation_index < 0)
     return root_to_self_task_ids;
 
   // The root task can be excluded. If so, consider the oldest ancestor
   // available as root.
   int root_navigation_index =
       task_id_and_root.root_navigation_index > excluded_navigation_num_
           ? task_id_and_root.root_navigation_index - excluded_navigation_num_
           : 0;
   for (int i = root_navigation_index; i <= navigation_position; i++) {
     // Fills the vector with valid tasks.
     if (task_ids_[i].root_navigation_index >= 0)
       root_to_self_task_ids.push_back(task_ids_[i].task_id);
   }
   return root_to_self_task_ids;
 }
 
 int TabTasks::GetNavigationsCount() const {
-  return GetNavigationIndexFromTaskIdPosition(task_ids_.size());
+  return excluded_navigation_num_ + task_ids_.size();
 }
 
 void TabTasks::UpdateWithNavigation(int navigation_index,
                                     ui::PageTransition transition,
                                     int64_t navigation_id) {
   // Triggered by some notifications on the current page, do nothing.
   if (navigation_index == current_navigation_index_) {
     DVLOG(1) << "Doing nothing for navigation_index: " << navigation_index
              << " of transition: " << transition;
     return;
   }
 
   // Going back/forward to some previous navigation.
   if (navigation_index < current_navigation_index_ ||
       (navigation_index > current_navigation_index_ &&
        transition & ui::PAGE_TRANSITION_FORWARD_BACK &&
        base::checked_cast<size_t>(navigation_index) < task_ids_.size())) {
     DVLOG(1) << "Just updating task position with navigation_index: "
              << navigation_index << " of transition: " << transition;
     current_navigation_index_ = navigation_index;
     return;
   }
 
   // A new task for the new navigation.
-  int root_navigation_index = source_tab_task_num_ + navigation_index;
-  if (ui::PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_LINK) ||
-      ui::PageTransitionCoreTypeIs(transition,
-                                   ui::PAGE_TRANSITION_AUTO_SUBFRAME) ||
-      ui::PageTransitionCoreTypeIs(transition,
-                                   ui::PAGE_TRANSITION_MANUAL_SUBFRAME) ||
-      ui::PageTransitionCoreTypeIs(transition,
-                                   ui::PAGE_TRANSITION_FORM_SUBMIT) ||
-      transition & ui::PAGE_TRANSITION_IS_REDIRECT_MASK) {
-    // Creating a sub-task with navigation at current_navigation_index_ as
-    // parent. If current_navigation_index_ == -1, the parent is the last task
-    // from source tab.
+  int root_navigation_index = navigation_index;
+  if (current_navigation_index_ != -1 &&
+      (ui::PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_LINK) ||
+       ui::PageTransitionCoreTypeIs(transition,
+                                    ui::PAGE_TRANSITION_AUTO_SUBFRAME) ||
+       ui::PageTransitionCoreTypeIs(transition,
+                                    ui::PAGE_TRANSITION_MANUAL_SUBFRAME) ||
+       ui::PageTransitionCoreTypeIs(transition,
+                                    ui::PAGE_TRANSITION_FORM_SUBMIT) ||
+       transition & ui::PAGE_TRANSITION_IS_REDIRECT_MASK)) {
+    // Creating a sub-task with navigation at current_navigation_index as
+    // parent.
     DVLOG(1) << "Creating a sub-task with navigation_index: "
              << navigation_index << " of transition: " << transition
              << " under navigation_index: " << current_navigation_index_;
-    // Position of current_navigation_index_ in task_id_
+    // Position in task_id_.
     int current_navigation_position =
-        GetTaskIdPositionFromNavigationIndex(current_navigation_index_);
-    // If current task, which is parent task of navigation_index, is excluded,
-    // consider the new task as a root task.
+        current_navigation_index_ - excluded_navigation_num_;
+    // If current/parent task is excluded, consider the new task as a root task.
     if (current_navigation_position >= 0) {
       CHECK_LT(current_navigation_position,
                base::checked_cast<int>(task_ids_.size()));
       root_navigation_index =
           task_ids_[current_navigation_position].root_navigation_index;
     } else {
       DVLOG(1) << "Becaue parent task is excluded, consider the sub-task as a "
                   "root task.";
     }
   } else {
     // Creating a root task.
     // For now, we don't consider tasks cross tabs, so first navigation of the
     // tab always creates a root task.
     DVLOG(1) << "Creating a root task with navigation_index: "
              << navigation_index << " of transition: " << transition;
   }
 
   // In most cases navigation_index == excluded_navigation_num_ +
-  // task_ids_.size() - source_tab_task_num_ if the previous navigation is end
-  // of chain, or navigation_index < excluded_navigation_num_ + task_ids_.size()
-  // otherwise. In few case navigation_index > excluded_navigation_num_ +
-  // task_ids_.size(), we fill task_ids_ with invalid contents. A known case is
-  // the first navigation after newtab.
-  for (int i = GetNavigationIndexFromTaskIdPosition(task_ids_.size());
+  // task_ids_.size() if the previous navigation is end of chain, or
+  // navigation_index < excluded_navigation_num_ + task_ids_.size() otherwise.
+  // In few case navigation_index > excluded_navigation_num_ + task_ids_.size(),
+  // we fill task_ids_ with invalid contents. A known case is the first
+  // navigation after newtab.
+  for (int i = task_ids_.size() + excluded_navigation_num_;
        i < navigation_index; i++) {
     task_ids_.push_back({-1, -1});
   }
 
-  int new_task_id_position =
-      GetTaskIdPositionFromNavigationIndex(navigation_index);
   // Erase all task ids associated with an outdated forward navigation stack.
-  if (new_task_id_position > 0) {
+  if (navigation_index > excluded_navigation_num_) {
+    int new_task_id_position = navigation_index - excluded_navigation_num_;
     task_ids_.erase(task_ids_.begin() + new_task_id_position, task_ids_.end());
   } else {
-    excluded_navigation_num_ = navigation_index + source_tab_task_num_;
+    excluded_navigation_num_ = navigation_index;
     // new task id position is 0
     task_ids_.clear();
   }
 
   // Exclude oldest ancestors if task number reaches the limit.
   int more_tasks_number = task_ids_.size() + 1 - kMaxNumTasksPerTab;
   if (more_tasks_number > 0) {
     task_ids_.erase(task_ids_.begin(), task_ids_.begin() + more_tasks_number);
     DVLOG(1) << "Excluding " << more_tasks_number
              << " oldest ancestor(s) from navigation index "
              << excluded_navigation_num_;
     excluded_navigation_num_ += more_tasks_number;
   }
 
   TaskIdAndRoot new_task = {root_navigation_index, navigation_id};
   // Add the current task at navigation_index.
   task_ids_.push_back(new_task);
   current_navigation_index_ = navigation_index;
   return;
 }
 
-int TabTasks::GetTaskIdPositionFromNavigationIndex(int navigation_index) const {
-  return source_tab_task_num_ + navigation_index - excluded_navigation_num_;
-}
-
-int TabTasks::GetNavigationIndexFromTaskIdPosition(int task_id_position) const {
-  return excluded_navigation_num_ + task_id_position - source_tab_task_num_;
-}
-
 TaskTracker::TaskTracker() {}
 
 TaskTracker::~TaskTracker() {}
 
 TabTasks* TaskTracker::GetTabTasks(SessionID::id_type tab_id) {
   if (local_tab_tasks_map_.find(tab_id) == local_tab_tasks_map_.end()) {
     local_tab_tasks_map_[tab_id] = base::MakeUnique<TabTasks>();
   }
   return local_tab_tasks_map_[tab_id].get();
 }
-
-TabTasks* TaskTracker::GetTabTasks(SessionID::id_type tab_id,
-                                   SessionID::id_type source_tab_id) {
-  if (local_tab_tasks_map_.find(tab_id) == local_tab_tasks_map_.end()) {
-    auto source_tab_iter = local_tab_tasks_map_.find(source_tab_id);
-    if (source_tab_iter != local_tab_tasks_map_.end()) {
-      local_tab_tasks_map_[tab_id] =
-          base::MakeUnique<TabTasks>(source_tab_iter->second.get());
-    } else {
-      local_tab_tasks_map_[tab_id] = base::MakeUnique<TabTasks>();
-    }
-  }
-  return local_tab_tasks_map_[tab_id].get();
-}
 
 void TaskTracker::CleanTabTasks(SessionID::id_type tab_id) {
   auto iter = local_tab_tasks_map_.find(tab_id);
   if (iter != local_tab_tasks_map_.end()) {
     local_tab_tasks_map_.erase(iter);
   }
 }
 
 }  // namespace sync_sessions