Update from https://crrev.com/304121

ui/gl/gl_fence_apple.cc

+// Copyright 2014 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 "ui/gl/gl_fence_apple.h"
+
+#include "ui/gl/gl_bindings.h"
+#include "ui/gl/gl_context.h"
+
+namespace gfx {
+
+GLFenceAPPLE::GLFenceAPPLE(bool flush) {
+  glGenFencesAPPLE(1, &fence_);
+  glSetFenceAPPLE(fence_);
+  DCHECK(glIsFenceAPPLE(fence_));
+  if (flush) {
+    glFlush();
+  } else {
+    flush_event_ = GLContext::GetCurrent()->SignalFlush();
+  }
+}
+
+bool GLFenceAPPLE::HasCompleted() {
+  DCHECK(glIsFenceAPPLE(fence_));
+  return !!glTestFenceAPPLE(fence_);
+}
+
+void GLFenceAPPLE::ClientWait() {
+  DCHECK(glIsFenceAPPLE(fence_));
+  if (!flush_event_.get() || flush_event_->IsSignaled()) {
+    glFinishFenceAPPLE(fence_);
+  } else {
+    LOG(ERROR) << "Trying to wait for uncommitted fence. Skipping...";
+  }
+}
+
+void GLFenceAPPLE::ServerWait() {
+  DCHECK(glIsFenceAPPLE(fence_));
+  ClientWait();
+}
+
+GLFenceAPPLE::~GLFenceAPPLE() {
+  DCHECK(glIsFenceAPPLE(fence_));
+  glDeleteFencesAPPLE(1, &fence_);
+}
+
+}  // namespace gfx