1 files changed, 51 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/threading/platform_thread.cc b/security/sandbox/chromium/base/threading/platform_thread.cc
new file mode 100644
index 0000000000..ae0a4499e7
--- /dev/null
+++ b/security/sandbox/chromium/base/threading/platform_thread.cc
@@ -0,0 +1,51 @@
+// Copyright 2018 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/threading/platform_thread.h"
+
+#include <atomic>
+#include <memory>
+
+#include "base/feature_list.h"
+
+namespace base {
+
+namespace {
+
+// Whether thread priorities should be used. When disabled,
+// PlatformThread::SetCurrentThreadPriority() no-ops.
+const Feature kThreadPrioritiesFeature{"ThreadPriorities",
+                                       FEATURE_ENABLED_BY_DEFAULT};
+
+// Whether thread priorities should be used.
+//
+// PlatformThread::SetCurrentThreadPriority() doesn't query the state of the
+// feature directly because FeatureList initialization is not always
+// synchronized with PlatformThread::SetCurrentThreadPriority().
+std::atomic<bool> g_use_thread_priorities(true);
+
+}  // namespace
+
+// static
+void PlatformThread::SetCurrentThreadPriority(ThreadPriority priority) {
+  if (g_use_thread_priorities.load())
+    SetCurrentThreadPriorityImpl(priority);
+}
+
+namespace internal {
+
+void InitializeThreadPrioritiesFeature() {
+  // A DCHECK is triggered on FeatureList initialization if the state of a
+  // feature has been checked before. To avoid triggering this DCHECK in unit
+  // tests that call this before initializing the FeatureList, only check the
+  // state of the feature if the FeatureList is initialized.
+  if (FeatureList::GetInstance() &&
+      !FeatureList::IsEnabled(kThreadPrioritiesFeature)) {
+    g_use_thread_priorities.store(false);
+  }
+}
+
+}  // namespace internal
+
+}  // namespace base