Update from https://crrev.com/304715

gpu/command_buffer/service/sync_point_manager.h

+// Copyright (c) 2012 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.
+
+#ifndef GPU_COMMAND_BUFFER_SERVICE_SYNC_POINT_MANAGER_H_
+#define GPU_COMMAND_BUFFER_SERVICE_SYNC_POINT_MANAGER_H_
+
+#include <vector>
+
+#include "base/callback.h"
+#include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
+#include "gpu/gpu_export.h"
+
+namespace gpu {
+
+// This class manages the sync points, which allow cross-channel
+// synchronization.
+class GPU_EXPORT SyncPointManager
+    : public base::RefCountedThreadSafe<SyncPointManager> {
+ public:
+  SyncPointManager();
+
+  // Generates a sync point, returning its ID. This can me called on any thread.
+  // IDs start at a random number. Never return 0.
+  uint32 GenerateSyncPoint();
+
+  // Retires a sync point. This will call all the registered callbacks for this
+  // sync point. This can only be called on the main thread.
+  void RetireSyncPoint(uint32 sync_point);
+
+  // Adds a callback to the sync point. The callback will be called when the
+  // sync point is retired, or immediately (from within that function) if the
+  // sync point was already retired (or not created yet). This can only be
+  // called on the main thread.
+  void AddSyncPointCallback(uint32 sync_point, const base::Closure& callback);
+
+  bool IsSyncPointRetired(uint32 sync_point);
+
+ private:
+  friend class base::RefCountedThreadSafe<SyncPointManager>;
+  typedef std::vector<base::Closure> ClosureList;
+  typedef base::hash_map<uint32, ClosureList> SyncPointMap;
+
+  ~SyncPointManager();
+
+  base::ThreadChecker thread_checker_;
+
+  // Protects the 2 fields below. Note: callbacks shouldn't be called with this
+  // held.
+  base::Lock lock_;
+  SyncPointMap sync_point_map_;
+  uint32 next_sync_point_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncPointManager);
+};
+
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_SYNC_POINT_MANAGER_H_