Add TaskPriority as a parameter to SequencedWorkerPool in preparation for TaskScheduler experiment.

net/disk_cache/blockfile/file_posix.cc

 // 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.
 
 #include "net/disk_cache/blockfile/file.h"
 
 #include <stdint.h>
 #include <limits>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/run_loop.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/disk_cache.h"
 
 namespace {
 
 // The maximum number of threads for this pool.
 const int kMaxThreads = 5;
 
 class FileWorkerPool : public base::SequencedWorkerPool {
  public:
-  FileWorkerPool() : base::SequencedWorkerPool(kMaxThreads, "CachePool") {}
+  FileWorkerPool()
+      : base::SequencedWorkerPool(kMaxThreads,
+                                  "CachePool",
+                                  base::TaskPriority::USER_BLOCKING) {}
 
  protected:
   ~FileWorkerPool() override {}
 };
 
 base::LazyInstance<FileWorkerPool>::Leaky s_worker_pool =
     LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
@@ skipping 140 matching lines @@
   return net::ERR_CACHE_WRITE_FAILURE;
 }
 
 // This method actually makes sure that the last reference to the file doesn't
 // go away on the worker pool.
 void File::OnOperationComplete(FileIOCallback* callback, int result) {
   callback->OnFileIOComplete(result);
 }
 
 }  // namespace disk_cache