1 files changed, 60 insertions, 0 deletions
diff --git a/dom/base/SameProcessMessageQueue.cpp b/dom/base/SameProcessMessageQueue.cpp
new file mode 100644
index 0000000000..bfeffd508a
--- /dev/null
+++ b/dom/base/SameProcessMessageQueue.cpp
@@ -0,0 +1,60 @@
+/* -*- 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/. */
+
+#include "SameProcessMessageQueue.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+SameProcessMessageQueue* SameProcessMessageQueue::sSingleton;
+
+SameProcessMessageQueue::SameProcessMessageQueue() = default;
+
+SameProcessMessageQueue::~SameProcessMessageQueue() {
+  // This code should run during shutdown, and we should already have pumped the
+  // event loop. So we should only see messages here if someone is sending
+  // messages pretty late in shutdown.
+  NS_WARNING_ASSERTION(mQueue.IsEmpty(),
+                       "Shouldn't send messages during shutdown");
+  sSingleton = nullptr;
+}
+
+void SameProcessMessageQueue::Push(Runnable* aRunnable) {
+  mQueue.AppendElement(aRunnable);
+  NS_DispatchToCurrentThread(aRunnable);
+}
+
+void SameProcessMessageQueue::Flush() {
+  const nsTArray<RefPtr<Runnable>> queue = std::move(mQueue);
+  for (size_t i = 0; i < queue.Length(); i++) {
+    queue[i]->Run();
+  }
+}
+
+/* static */
+SameProcessMessageQueue* SameProcessMessageQueue::Get() {
+  if (!sSingleton) {
+    sSingleton = new SameProcessMessageQueue();
+  }
+  return sSingleton;
+}
+
+SameProcessMessageQueue::Runnable::Runnable() : mDispatched(false) {}
+
+NS_IMPL_ISUPPORTS(SameProcessMessageQueue::Runnable, nsIRunnable)
+
+nsresult SameProcessMessageQueue::Runnable::Run() {
+  if (mDispatched) {
+    return NS_OK;
+  }
+
+  SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
+  queue->mQueue.RemoveElement(this);
+
+  mDispatched = true;
+  return HandleMessage();
+}