Remove dependency of SSLPlatformKeyTaskRunner on single-threaded SequencedWorkerPool.

net/ssl/ssl_platform_key_task_runner.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/lazy_instance.h"
+#include "base/logging.h"
+#include "base/single_thread_task_runner.h"
 #include "net/ssl/ssl_platform_key_task_runner.h"
 
 namespace net {
 
-SSLPlatformKeyTaskRunner::SSLPlatformKeyTaskRunner() {
-  worker_pool_ = new base::SequencedWorkerPool(1, "Platform Key Thread");
-  task_runner_ = worker_pool_->GetSequencedTaskRunnerWithShutdownBehavior(
-      worker_pool_->GetSequenceToken(),
-      base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
-}
-
-SSLPlatformKeyTaskRunner::~SSLPlatformKeyTaskRunner() {}
-
-scoped_refptr<base::SequencedTaskRunner>
-SSLPlatformKeyTaskRunner::task_runner() {
-  return task_runner_;
-}
+namespace {
 
 base::LazyInstance<SSLPlatformKeyTaskRunner>::Leaky g_platform_key_task_runner =
     LAZY_INSTANCE_INITIALIZER;
 
-scoped_refptr<base::SequencedTaskRunner> GetSSLPlatformKeyTaskRunner() {
-  return g_platform_key_task_runner.Get().task_runner();
+}  // namespace
+
+SSLPlatformKeyTaskRunner::SSLPlatformKeyTaskRunner()
+    : worker_thread_("Platform Key Thread") {
+  worker_thread_.Start();
+}
+
+// static
+scoped_refptr<base::SingleThreadTaskRunner> SSLPlatformKeyTaskRunner::Get() {
+  scoped_refptr<base::SingleThreadTaskRunner> ssl_task_runner =
+      g_platform_key_task_runner.Get().worker_thread_.task_runner();
+  DCHECK(ssl_task_runner);
+  return ssl_task_runner;
 }
 
 }  // namespace net