import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

layout/ipc/VsyncChild.h

@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layout_ipc_VsyncChild_h
+#define mozilla_layout_ipc_VsyncChild_h
+
+#include "mozilla/layout/PVsyncChild.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+
+class VsyncObserver;
+
+namespace ipc {
+class BackgroundChildImpl;
+} // namespace ipc
+
+namespace layout {
+
+// The PVsyncChild actor receives a vsync event from the main process and
+// delivers it to the child process. Currently this is restricted to the main
+// thread only. The actor will stay alive until the process dies or its
+// PVsyncParent actor dies.
+class VsyncChild final : public PVsyncChild
+{
+  NS_INLINE_DECL_REFCOUNTING(VsyncChild)
+
+  friend class mozilla::ipc::BackgroundChildImpl;
+
+public:
+  // Hide the SendObserve/SendUnobserve in PVsyncChild. We add an flag
+  // mObservingVsync to handle the race problem of unobserving vsync event.
+  bool SendObserve();
+  bool SendUnobserve();
+
+  // Bind a VsyncObserver into VsyncChild after ipc channel connected.
+  void SetVsyncObserver(VsyncObserver* aVsyncObserver);
+  TimeDuration GetVsyncRate();
+
+private:
+  VsyncChild();
+  virtual ~VsyncChild();
+
+  virtual bool RecvNotify(const TimeStamp& aVsyncTimestamp) override;
+  virtual bool RecvVsyncRate(const float& aVsyncRate) override;
+  virtual void ActorDestroy(ActorDestroyReason aActorDestroyReason) override;
+
+  bool mObservingVsync;
+  bool mIsShutdown;
+
+  // The content side vsync observer.
+  RefPtr<VsyncObserver> mObserver;
+  TimeDuration mVsyncRate;
+};
+
+} // namespace layout
+} // namespace mozilla
+
+#endif  // mozilla_layout_ipc_VsyncChild_h