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

chrome/browser/chromeos/net/client_cert_store_chromeos.cc

 // Copyright 2013 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 "chrome/browser/chromeos/net/client_cert_store_chromeos.h"
 
 #include <cert.h>
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
-#include "base/task_scheduler/post_task.h"
+#include "base/threading/worker_pool.h"
 #include "chrome/browser/chromeos/certificate_provider/certificate_provider.h"
 #include "crypto/nss_crypto_module_delegate.h"
 #include "net/ssl/ssl_cert_request_info.h"
 
 namespace chromeos {
 
 namespace {
 
 class CertNotAllowedPredicate {
  public:
@@ skipping 48 matching lines @@
     const net::SSLCertRequestInfo* request,
     net::CertificateList* selected_certs,
     const base::Closure& callback,
     const net::CertificateList& additional_certs) {
   std::unique_ptr<crypto::CryptoModuleBlockingPasswordDelegate>
       password_delegate;
   if (!password_delegate_factory_.is_null()) {
     password_delegate.reset(
         password_delegate_factory_.Run(request->host_and_port));
   }
-  base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock().WithShutdownBehavior(
-                     base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
-      base::Bind(&ClientCertStoreChromeOS::GetAndFilterCertsOnWorkerThread,
-                 base::Unretained(this), base::Passed(&password_delegate),
-                 request, additional_certs, selected_certs),
-      callback);
+  if (base::WorkerPool::PostTaskAndReply(

[gab, 2017/02/28 01:42:40]

Probably don't need to bring back handling PostTask returning false?

+          FROM_HERE,
+          base::Bind(&ClientCertStoreChromeOS::GetAndFilterCertsOnWorkerThread,
+                     base::Unretained(this), base::Passed(&password_delegate),
+                     request, additional_certs, selected_certs),
+          callback, true)) {
+    return;
+  }
+  // If the task could not be posted, behave as if there were no certificates
+  // which requires to clear |selected_certs|.
+  selected_certs->clear();
+  callback.Run();
 }
 
 void ClientCertStoreChromeOS::GetAndFilterCertsOnWorkerThread(
     std::unique_ptr<crypto::CryptoModuleBlockingPasswordDelegate>
         password_delegate,
     const net::SSLCertRequestInfo* request,
     const net::CertificateList& additional_certs,
     net::CertificateList* selected_certs) {
   net::CertificateList unfiltered_certs;
   net::ClientCertStoreNSS::GetPlatformCertsOnWorkerThread(
       std::move(password_delegate), &unfiltered_certs);
 
   unfiltered_certs.erase(
       std::remove_if(unfiltered_certs.begin(), unfiltered_certs.end(),
                      CertNotAllowedPredicate(cert_filter_.get())),
       unfiltered_certs.end());
 
   unfiltered_certs.insert(unfiltered_certs.end(), additional_certs.begin(),
                           additional_certs.end());
 
   net::ClientCertStoreNSS::FilterCertsOnWorkerThread(unfiltered_certs, *request,
                                                      selected_certs);
 }
 
 }  // namespace chromeos