Revert of Use TaskScheduler instead of WorkerPool in nss_cert_database.cc.

net/cert/nss_cert_database.cc

Index: net/cert/nss_cert_database.cc
diff --git a/net/cert/nss_cert_database.cc b/net/cert/nss_cert_database.cc
index 14aa891ed6244d883dfcc5ea6b848857ae5813b3..98f6882543cd6b9c8e980b032ab20ce69dadc8f5 100644
--- a/net/cert/nss_cert_database.cc
+++ b/net/cert/nss_cert_database.cc
@@ -18,7 +18,9 @@
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/observer_list_threadsafe.h"
-#include "base/task_scheduler/post_task.h"
+#include "base/task_runner.h"
+#include "base/task_runner_util.h"
+#include "base/threading/worker_pool.h"
 #include "crypto/scoped_nss_types.h"
 #include "net/base/crypto_module.h"
 #include "net/base/net_errors.h"
@@ -100,14 +102,10 @@ void NSSCertDatabase::ListCerts(
 
   // base::Passed will NULL out |certs|, so cache the underlying pointer here.
   CertificateList* raw_certs = certs.get();
-  base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits()
-                     .WithShutdownBehavior(
-                         base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN)
-                     .MayBlock(),
-      base::Bind(&NSSCertDatabase::ListCertsImpl,
-                 base::Passed(crypto::ScopedPK11Slot()),
-                 base::Unretained(raw_certs)),
+  GetSlowTaskRunner()->PostTaskAndReply(
+      FROM_HERE, base::Bind(&NSSCertDatabase::ListCertsImpl,
+                            base::Passed(crypto::ScopedPK11Slot()),
+                            base::Unretained(raw_certs)),
       base::Bind(callback, base::Passed(&certs)));
 }
 
@@ -118,11 +116,8 @@ void NSSCertDatabase::ListCertsInSlot(const ListCertsCallback& callback,
 
   // base::Passed will NULL out |certs|, so cache the underlying pointer here.
   CertificateList* raw_certs = certs.get();
-  base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits()
-                     .WithShutdownBehavior(
-                         base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN)
-                     .MayBlock(),
+  GetSlowTaskRunner()->PostTaskAndReply(
+      FROM_HERE,
       base::Bind(&NSSCertDatabase::ListCertsImpl,
                  base::Passed(crypto::ScopedPK11Slot(PK11_ReferenceSlot(slot))),
                  base::Unretained(raw_certs)),
@@ -381,11 +376,8 @@ bool NSSCertDatabase::DeleteCertAndKey(X509Certificate* cert) {
 void NSSCertDatabase::DeleteCertAndKeyAsync(
     const scoped_refptr<X509Certificate>& cert,
     const DeleteCertCallback& callback) {
-  base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits()
-                     .WithShutdownBehavior(
-                         base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN)
-                     .MayBlock(),
+  base::PostTaskAndReplyWithResult(
+      GetSlowTaskRunner().get(), FROM_HERE,
       base::Bind(&NSSCertDatabase::DeleteCertAndKeyImpl, cert),
       base::Bind(&NSSCertDatabase::NotifyCertRemovalAndCallBack,
                  weak_factory_.GetWeakPtr(), callback));
@@ -409,6 +401,11 @@ void NSSCertDatabase::RemoveObserver(Observer* observer) {
   observer_list_->RemoveObserver(observer);
 }
 
+void NSSCertDatabase::SetSlowTaskRunnerForTest(
+    const scoped_refptr<base::TaskRunner>& task_runner) {
+  slow_task_runner_for_test_ = task_runner;
+}
+
 // static
 void NSSCertDatabase::ListCertsImpl(crypto::ScopedPK11Slot slot,
                                     CertificateList* certs) {
@@ -429,6 +426,12 @@ void NSSCertDatabase::ListCertsImpl(crypto::ScopedPK11Slot slot,
   CERT_DestroyCertList(cert_list);
 }
 
+scoped_refptr<base::TaskRunner> NSSCertDatabase::GetSlowTaskRunner() const {
+  if (slow_task_runner_for_test_.get())
+    return slow_task_runner_for_test_;
+  return base::WorkerPool::GetTaskRunner(true /*task is slow*/);
+}
+
 void NSSCertDatabase::NotifyCertRemovalAndCallBack(
     const DeleteCertCallback& callback,
     bool success) {