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diff --git a/ipc/glue/BackgroundChild.h b/ipc/glue/BackgroundChild.h
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+/* -*- 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_ipc_backgroundchild_h__
+#define mozilla_ipc_backgroundchild_h__
+
+#include "mozilla/Attributes.h"
+
+class nsIEventTarget;
+
+namespace mozilla {
+namespace dom {
+
+class BlobImpl;
+class ContentChild;
+class ContentParent;
+class ContentProcess;
+
+}  // namespace dom
+
+namespace ipc {
+
+class PBackgroundChild;
+class PBackgroundStarterChild;
+
+// This class allows access to the PBackground protocol. PBackground allows
+// communication between any thread (in the parent or a child process) and a
+// single background thread in the parent process. Each PBackgroundChild
+// instance is tied to the thread on which it is created and must not be shared
+// across threads. Each PBackgroundChild is unique and valid as long as its
+// designated thread lives.
+//
+// Creation of PBackground is synchronous. GetOrCreateForCurrentThread will
+// create the actor if it doesn't exist yet. Thereafter (assuming success)
+// GetForCurrentThread() will return the same actor every time.
+//
+// CloseForCurrentThread() will close the current PBackground actor.  Subsequent
+// calls to GetForCurrentThread will return null.  CloseForCurrentThread() may
+// only be called exactly once for each thread-specific actor.  Currently it is
+// illegal to call this before the PBackground actor has been created.
+//
+// The PBackgroundChild actor and all its sub-protocol actors will be
+// automatically destroyed when its designated thread completes.
+//
+// InitContentStarter must be called on the main thread
+// with an actor bridging to the relevant target process type before these
+// methods can be used.
+class BackgroundChild final {
+  friend class mozilla::dom::ContentParent;
+  friend class mozilla::dom::ContentProcess;
+
+ public:
+  // See above.
+  static PBackgroundChild* GetForCurrentThread();
+
+  // See above.
+  static PBackgroundChild* GetOrCreateForCurrentThread();
+
+  // See above.
+  static void CloseForCurrentThread();
+
+  // See above.
+  static void InitContentStarter(mozilla::dom::ContentChild* aContent);
+
+ private:
+  // Only called by this class's friends.
+  static void Startup();
+};
+
+}  // namespace ipc
+}  // namespace mozilla
+
+#endif  // mozilla_ipc_backgroundchild_h__