1 files changed, 57 insertions, 0 deletions
diff --git a/widget/android/WindowEvent.h b/widget/android/WindowEvent.h
new file mode 100644
index 0000000000..fdb73bf692
--- /dev/null
+++ b/widget/android/WindowEvent.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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_widget_WindowEvent_h
+#define mozilla_widget_WindowEvent_h
+
+#include "nsThreadUtils.h"
+#include "mozilla/jni/Natives.h"
+
+namespace mozilla {
+namespace widget {
+
+// An Event subclass that guards against stale events.
+// (See the implmentation of mozilla::jni::detail::ProxyNativeCall for info
+//  about the default template parameters for this class)
+template <typename Lambda, bool IsStatic = Lambda::isStatic,
+          typename InstanceType = typename Lambda::ThisArgType,
+          class Impl = typename Lambda::TargetClass>
+class WindowEvent : public Runnable {
+  bool IsStaleCall() {
+    if (IsStatic) {
+      // Static calls are never stale.
+      return false;
+    }
+
+    return jni::NativePtrTraits<Impl>::IsStale(mInstance);
+  }
+
+  Lambda mLambda;
+  const InstanceType mInstance;
+
+ public:
+  WindowEvent(Lambda&& aLambda, InstanceType&& aInstance)
+      : Runnable("mozilla::widget::WindowEvent"),
+        mLambda(std::move(aLambda)),
+        mInstance(std::forward<InstanceType>(aInstance)) {}
+
+  explicit WindowEvent(Lambda&& aLambda)
+      : Runnable("mozilla::widget::WindowEvent"),
+        mLambda(std::move(aLambda)),
+        mInstance(mLambda.GetThisArg()) {}
+
+  NS_IMETHOD Run() override {
+    if (!IsStaleCall()) {
+      mLambda();
+    }
+    return NS_OK;
+  }
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // mozilla_widget_WindowEvent_h