fuchsia: Implement platform thread functions

base/threading/platform_thread_fuchsia.cc

+// Copyright 2017 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 <pthread.h>
+#include <sched.h>
+
+#include "base/threading/platform_thread_internal_posix.h"
+
+namespace base {
+
+namespace internal {
+
+const ThreadPriorityToNiceValuePair kThreadPriorityToNiceValueMap[4] = {
+    {ThreadPriority::BACKGROUND, 10},
+    {ThreadPriority::NORMAL, 0},
+    {ThreadPriority::DISPLAY, -8},
+    {ThreadPriority::REALTIME_AUDIO, -10},
+};
+
+bool SetCurrentThreadPriorityForPlatform(ThreadPriority priority) {
+  sched_param prio = {0};
+  prio.sched_priority = ThreadPriorityToNiceValue(priority);
+  return pthread_setschedparam(pthread_self(), SCHED_OTHER, &prio) == 0;
+}
+
+bool GetCurrentThreadPriorityForPlatform(ThreadPriority* priority) {
+  sched_param prio = {0};
+  int policy;
+  if (pthread_getschedparam(pthread_self(), &policy, &prio) != 0) {
+    return false;
+  }
+  *priority = NiceValueToThreadPriority(prio.sched_priority);
+  return true;
+}
+
+}  // namespace internal
+
+void InitThreading() {}
+
+void TerminateOnThread() {}
+
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes) {
+  return 0;
+}
+
+// static
+void PlatformThread::SetName(const std::string& name) {
+  // TODO(fuchsia): There's no available API at the moment to set the thread
+  // name. See https://crbug.com/725726.
+}
+
+}  // namespace base