Implemented new fence syncs which replaces the old sync points.

gpu/command_buffer/service/fence_sync_manager.h

Index: gpu/command_buffer/service/fence_sync_manager.h
diff --git a/gpu/command_buffer/service/fence_sync_manager.h b/gpu/command_buffer/service/fence_sync_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..fc59d432cd3c69c627e7029fb63594ba5dd08182
--- /dev/null
+++ b/gpu/command_buffer/service/fence_sync_manager.h
@@ -0,0 +1,61 @@
+// Copyright (c) 2015 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_FENCE_MANAGER_H_
+#define GPU_COMMAND_BUFFER_SERVICE_SYNC_FENCE_MANAGER_H_
+
+#include <functional>
+#include <queue>
+
+#include "base/callback.h"
+#include "gpu/gpu_export.h"
+
+namespace gpu {
+
+// This class manages the sync fences, which allow cross-channel
+// synchronization.
+class GPU_EXPORT FenceSyncManager {
+ public:
+  FenceSyncManager();
+  ~FenceSyncManager();
+
+  void AddFenceSyncCallback(uint32_t max_order_number,
+                            uint32_t release,
+                            const base::Closure& callback);
+
+  bool IsFenceSyncReleased(uint32_t release) const {
+    return release <= fence_sync_release_;
+  }
+
+  void ReleaseFenceSync(uint32_t release);
+
+ private:
+  struct FenceSyncCallback {
+    uint32_t release_count;
+    base::Closure callback_closure;
+
+    FenceSyncCallback(uint32_t release, const base::Closure& callback);
+    ~FenceSyncCallback();
+
+    bool operator>(const FenceSyncCallback& rhs) const {
+      return release_count > rhs.release_count;
+    }
+  };
+  typedef std::priority_queue<FenceSyncCallback,
+                              std::vector<FenceSyncCallback>,
+                              std::greater<FenceSyncCallback>> CallbackQueue;
+
+  // Current fence sync release that has been signaled.
+  uint32_t fence_sync_release_;
+
+  // In well defined fence sync operations, fence syncs are released in order
+  // so simply having a priority queue for callbacks is enough.
+  CallbackQueue fence_callback_queue_;
+
+  DISALLOW_COPY_AND_ASSIGN(FenceSyncManager);
+};
+
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_SYNC_FENCE_MANAGER_H_