Switch a ThreadedTaskRunnerHandle to SequencedTaskRunnerHandle

rsleevi pointed out this didn't need to be thread-affine. (I've long
since lost track of what all our random PostTask hooks do...)

Bug: none
Change-Id: I6d7dc61684202383787012853bb55fab8376d42c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1904123
Auto-Submit: David Benjamin <davidben@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713625}

chrome/browser/chromeos/certificate_provider/certificate_provider_service.cc

@@ -19,7 +19,7 @@
 #include "base/strings/string_piece.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
-#include "base/threading/thread_task_runner_handle.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #include "chrome/browser/chromeos/certificate_provider/certificate_provider.h"
 #include "net/base/net_errors.h"
 #include "third_party/boringssl/src/include/openssl/digest.h"
@@ -32,14 +32,14 @@ namespace {
 void PostSignResult(net::SSLPrivateKey::SignCallback callback,
                     net::Error error,
                     const std::vector<uint8_t>& signature) {
-  base::ThreadTaskRunnerHandle::Get()->PostTask(
+  base::SequencedTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::BindOnce(std::move(callback), error, signature));
 }
 
 void PostIdentities(
     base::OnceCallback<void(net::ClientCertIdentityList)> callback,
     net::ClientCertIdentityList certs) {
-  base::ThreadTaskRunnerHandle::Get()->PostTask(
+  base::SequencedTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::BindOnce(std::move(callback), std::move(certs)));
 }