Allow SequencedTaskRunnerHandle::Get() while running unsequenced tasks.

base/threading/sequenced_task_runner_handle.cc

 // Copyright 2015 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 "base/threading/sequenced_task_runner_handle.h"
 
 #include "base/sequenced_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/sequenced_worker_pool.h"
 
 namespace base {
 
 // static
 scoped_refptr<SequencedTaskRunner> SequencedTaskRunnerHandle::Get() {
-  // If we are on a worker thread for a SequencedBlockingPool that is running a
-  // sequenced task, return a SequencedTaskRunner for it.
-  scoped_refptr<base::SequencedWorkerPool> pool =
-      SequencedWorkerPool::GetWorkerPoolForCurrentThread();
-  if (pool) {
-    SequencedWorkerPool::SequenceToken sequence_token =
-        SequencedWorkerPool::GetSequenceTokenForCurrentThread();
-    DCHECK(sequence_token.IsValid());
-    DCHECK(pool->IsRunningSequenceOnCurrentThread(sequence_token));
-    return pool->GetSequencedTaskRunner(sequence_token);
-  }
-
-  // Otherwise, return a SingleThreadTaskRunner for the current thread.
-  return base::ThreadTaskRunnerHandle::Get();
+  // Return the SequencedTaskRunner if found or the SingleThreadedTaskRunner for
+  // the current thread otherwise.
+  scoped_refptr<base::SequencedTaskRunner> task_runner =
+      SequencedWorkerPool::GetSequencedTaskRunnerForCurrentThread();
+  return task_runner ? task_runner : scoped_refptr<SequencedTaskRunner>(

[danakj, 2015/11/17 22:03:39]

I liked without the ?: better >__>

[Bernhard Bauer, 2015/11/18 13:15:50]

FWIW, I agree, so I changed it back to two return statements for now. Gab, do
you feel strongly about this?

[gab, 2015/11/18 22:37:33]

Nope, either way is fine (would have preferred this if it wasn't for the ugly
cast).

+                                         base::ThreadTaskRunnerHandle::Get());
 }
 
 // static
 bool SequencedTaskRunnerHandle::IsSet() {
-  return (SequencedWorkerPool::GetWorkerPoolForCurrentThread() &&
-          SequencedWorkerPool::GetSequenceTokenForCurrentThread().IsValid()) ||
+  return SequencedWorkerPool::GetSequencedTaskRunnerForCurrentThread() ||
          base::ThreadTaskRunnerHandle::IsSet();
 }
 
 }  // namespace base