ui: Add libsync GLFence implementation.

gpu/ipc/client/gpu_fence_impl_libsync.cc

+// Copyright 2016 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 "gpu/ipc/client/gpu_fence_impl_libsync.h"
+
+#include "third_party/libsync/include/sync/sync.h"
+
+namespace gpu {
+
+GpuFenceImplLibsync::GpuFenceImplLibsync(const base::FileDescriptor& fd)
+    : fd_(fd.fd) {}
+
+GpuFenceImplLibsync::~GpuFenceImplLibsync() {}
+
+bool GpuFenceImplLibsync::IsSignaled() {
+  int rv = sync_wait(fd_.get(), 0);
+  PLOG_IF(ERROR, rv < 0) << "sync_wait failed: " << rv;
+  return !rv;
+}
+
+bool GpuFenceImplLibsync::Wait(const base::TimeDelta& max_time) {
+  int rv = sync_wait(fd_.get(), max_time.InMilliseconds());
+  PLOG_IF(ERROR, rv < 0) << "sync_wait failed: " << rv;
+  return !rv;
+}
+
+gfx::GpuFenceHandle GpuFenceImplLibsync::GetHandle() const {
+  gfx::GpuFenceHandle handle;
+  handle.fd.fd = fd_.get();
+  handle.fd.auto_close = false;
+  return handle;
+}
+
+}  // namespace gpu