import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

gfx/layers/IPDLActor.h

@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 20; 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_LAYERS_IPDLACTOR_H
+#define MOZILLA_LAYERS_IPDLACTOR_H
+
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/layers/CompositableForwarder.h"
+#include "mozilla/Unused.h"
+#include "gfxPlatform.h"
+
+namespace mozilla {
+namespace layers {
+
+/// A base class to facilitate the deallocation of IPDL actors.
+///
+/// Implements the parent side of the simple deallocation handshake.
+/// Override the Destroy method rather than the ActorDestroy method.
+template<typename Protocol>
+class ParentActor : public Protocol
+{
+public:
+  ParentActor() : mDestroyed(false) {}
+
+  ~ParentActor() { MOZ_ASSERT(mDestroyed); }
+
+  bool CanSend() const { return !mDestroyed; }
+
+  // Override this rather than ActorDestroy
+  virtual void Destroy() {}
+
+  virtual bool RecvDestroy() override
+  {
+    DestroyIfNeeded();
+    Unused << Protocol::Send__delete__(this);
+    return true;
+  }
+
+  typedef ipc::IProtocol::ActorDestroyReason Why;
+
+  virtual void ActorDestroy(Why) override {
+    DestroyIfNeeded();
+  }
+
+protected:
+  void DestroyIfNeeded() {
+    if (!mDestroyed) {
+      Destroy();
+      mDestroyed = true;
+    }
+  }
+
+private:
+  bool mDestroyed;
+};
+
+} // namespace
+} // namespace
+
+#endif