Mozart: Generalize frame scheduling.

services/gfx/compositor/frame_dispatcher.h

+// 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.
+
+#ifndef SERVICES_GFX_COMPOSITOR_FRAME_DISPATCHER_H_
+#define SERVICES_GFX_COMPOSITOR_FRAME_DISPATCHER_H_
+
+#include <vector>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "mojo/services/gfx/composition/interfaces/scheduling.mojom.h"
+
+namespace compositor {
+
+using FrameCallback =
+    base::Callback<void(mojo::gfx::composition::FrameInfoPtr)>;
+
+// Maintains a list of pending frame callbacks to be dispatched.
+class FrameDispatcher {
+ public:
+  FrameDispatcher();
+  ~FrameDispatcher();
+
+  // Adds a callback, returns true if it was the first pending callback.
+  bool AddCallback(const FrameCallback& callback);
+
+  // Dispatches all pending callbacks then clears the list.
+  void DispatchCallbacks(const mojo::gfx::composition::FrameInfo& frame_info);
+
+ private:
+  std::vector<FrameCallback> pending_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(FrameDispatcher);
+};
+
+}  // namespace compositor
+
+#endif  // SERVICES_GFX_COMPOSITOR_FRAME_DISPATCHER_H_