Update from https://crrev.com/327068

base/threading/sequenced_worker_pool.h

 // Copyright (c) 2012 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 BASE_THREADING_SEQUENCED_WORKER_POOL_H_
 #define BASE_THREADING_SEQUENCED_WORKER_POOL_H_
 
 #include <cstddef>
 #include <string>
 
@@ skipping 302 matching lines @@
   // Spuriously signal that there is work to be done.
   void SignalHasWorkForTesting();
 
   // Implements the worker pool shutdown. This should be called during app
   // shutdown, and will discard/join with appropriate tasks before returning.
   // After this call, subsequent calls to post tasks will fail.
   //
   // Must be called from the same thread this object was constructed on.
   void Shutdown() { Shutdown(0); }
 
-  // A variant that allows an arbitrary number of new blocking tasks to
-  // be posted during shutdown from within tasks that execute during shutdown.
-  // Only tasks designated as BLOCKING_SHUTDOWN will be allowed, and only if
-  // posted by tasks that are not designated as CONTINUE_ON_SHUTDOWN. Once
+  // A variant that allows an arbitrary number of new blocking tasks to be
+  // posted during shutdown. The tasks cannot be posted within the execution
+  // context of tasks whose shutdown behavior is not BLOCKING_SHUTDOWN. Once
   // the limit is reached, subsequent calls to post task fail in all cases.
-  //
   // Must be called from the same thread this object was constructed on.
   void Shutdown(int max_new_blocking_tasks_after_shutdown);
 
   // Check if Shutdown was called for given threading pool. This method is used
   // for aborting time consuming operation to avoid blocking shutdown.
   //
   // Can be called from any thread.
   bool IsShutdownInProgress();
 
  protected:
@@ skipping 13 matching lines @@
   // Avoid pulling in too many headers by putting (almost) everything
   // into |inner_|.
   const scoped_ptr<Inner> inner_;
 
   DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPool);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_SEQUENCED_WORKER_POOL_H_