Revert of Force HostContentSettingsMap to be destroyed on its owning thread.

base/threading/sequenced_worker_pool.cc

Index: base/threading/sequenced_worker_pool.cc
diff --git a/base/threading/sequenced_worker_pool.cc b/base/threading/sequenced_worker_pool.cc
index af22098effca47dbeb484d95244f1bd1a928819e..56bbb62dd09f58bb92f05340598a109e715c5aee 100644
--- a/base/threading/sequenced_worker_pool.cc
+++ b/base/threading/sequenced_worker_pool.cc
@@ -383,12 +383,6 @@
     CLEANUP_DONE,
   };
 
-  // Clears ScheduledTasks in |tasks_to_delete| while ensuring that
-  // |this_worker| has the desired task info context during ~ScheduledTask() to
-  // allow sequence-checking.
-  void DeleteWithoutLock(std::vector<SequencedTask>* tasks_to_delete,
-                         Worker* this_worker);
-
   // Helper used by PostTask() to complete the work when redirection is on.
   // Returns true if the task may run at some point in the future and false if
   // it will definitely not run.
@@ -426,7 +420,7 @@
   // See the implementation for a more detailed description.
   GetWorkStatus GetWork(SequencedTask* task,
                         TimeDelta* wait_time,
-                        std::vector<SequencedTask>* delete_these_outside_lock);
+                        std::vector<Closure>* delete_these_outside_lock);
 
   void HandleCleanup();
 
@@ -989,7 +983,7 @@
       // See GetWork for what delete_these_outside_lock is doing.
       SequencedTask task;
       TimeDelta wait_time;
-      std::vector<SequencedTask> delete_these_outside_lock;
+      std::vector<Closure> delete_these_outside_lock;
       GetWorkStatus status =
           GetWork(&task, &wait_time, &delete_these_outside_lock);
       if (status == GET_WORK_FOUND) {
@@ -1006,7 +1000,7 @@
           // already get a signal for each new task, but it doesn't
           // hurt.)
           SignalHasWork();
-          DeleteWithoutLock(&delete_these_outside_lock, this_worker);
+          delete_these_outside_lock.clear();
 
           // Complete thread creation outside the lock if necessary.
           if (new_thread_id)
@@ -1037,7 +1031,7 @@
         switch (status) {
           case GET_WORK_WAIT: {
               AutoUnlock unlock(lock_);
-              DeleteWithoutLock(&delete_these_outside_lock, this_worker);
+              delete_these_outside_lock.clear();
             }
             break;
           case GET_WORK_NOT_FOUND:
@@ -1059,7 +1053,7 @@
         // help this case.
         if (shutdown_called_ && blocking_shutdown_pending_task_count_ == 0) {
           AutoUnlock unlock(lock_);
-          DeleteWithoutLock(&delete_these_outside_lock, this_worker);
+          delete_these_outside_lock.clear();
           break;
         }
 
@@ -1067,7 +1061,7 @@
         // deletion must happen outside of the lock.
         if (delete_these_outside_lock.size()) {
           AutoUnlock unlock(lock_);
-          DeleteWithoutLock(&delete_these_outside_lock, this_worker);
+          delete_these_outside_lock.clear();
 
           // Since the lock has been released, |status| may no longer be
           // accurate. It might read GET_WORK_WAIT even if there are tasks
@@ -1090,9 +1084,6 @@
         }
         waiting_thread_count_--;
       }
-      // |delete_these_outside_lock| should have been cleared via
-      // DeleteWithoutLock() above already.
-      DCHECK(delete_these_outside_lock.empty());
     }
   }  // Release lock_.
 
@@ -1102,19 +1093,6 @@
 
   // Possibly unblock shutdown.
   can_shutdown_cv_.Signal();
-}
-
-void SequencedWorkerPool::Inner::DeleteWithoutLock(
-    std::vector<SequencedTask>* tasks_to_delete,
-    Worker* this_worker) {
-  while (!tasks_to_delete->empty()) {
-    const SequencedTask& deleted_task = tasks_to_delete->back();
-    this_worker->set_running_task_info(
-        SequenceToken(deleted_task.sequence_token_id),
-        deleted_task.shutdown_behavior);
-    tasks_to_delete->pop_back();
-  }
-  this_worker->reset_running_task_info();
 }
 
 void SequencedWorkerPool::Inner::HandleCleanup() {
@@ -1184,7 +1162,7 @@
 SequencedWorkerPool::Inner::GetWorkStatus SequencedWorkerPool::Inner::GetWork(
     SequencedTask* task,
     TimeDelta* wait_time,
-    std::vector<SequencedTask>* delete_these_outside_lock) {
+    std::vector<Closure>* delete_these_outside_lock) {
   DCHECK_EQ(AllPoolsState::USE_WORKER_POOL, g_all_pools_state);
 
   lock_.AssertAcquired();
@@ -1230,17 +1208,18 @@
       // shutdown. Delete it and get more work.
       //
       // Note that we do not want to delete unrunnable tasks. Deleting a task
-      // can have side effects (like freeing some objects) and deleting a task
-      // that's supposed to run after one that's currently running could cause
-      // an obscure crash.
+      // can have side effects (like freeing some objects) and deleting a
+      // task that's supposed to run after one that's currently running could
+      // cause an obscure crash.
       //
       // We really want to delete these tasks outside the lock in case the
-      // closures are holding refs to objects that want to post work from their
-      // destructors (which would deadlock). The closures are internally
-      // refcounted, so we just need to keep a copy of them alive until the lock
-      // is exited. The calling code can just clear() the vector they passed to
-      // us once the lock is exited to make this happen.
-      delete_these_outside_lock->push_back(*i);
+      // closures are holding refs to objects that want to post work from
+      // their destructorss (which would deadlock). The closures are
+      // internally refcounted, so we just need to keep a copy of them alive
+      // until the lock is exited. The calling code can just clear() the
+      // vector they passed to us once the lock is exited to make this
+      // happen.
+      delete_these_outside_lock->push_back(i->task);
       pending_tasks_.erase(i++);
       continue;
     }
@@ -1251,7 +1230,7 @@
       status = GET_WORK_WAIT;
       if (cleanup_state_ == CLEANUP_RUNNING) {
         // Deferred tasks are deleted when cleaning up, see Inner::ThreadLoop.
-        delete_these_outside_lock->push_back(*i);
+        delete_these_outside_lock->push_back(i->task);
         pending_tasks_.erase(i);
       }
       break;