attachment broker wip

ipc/brokerable_attachment.h

Index: ipc/brokerable_attachment.h
diff --git a/ipc/brokerable_attachment.h b/ipc/brokerable_attachment.h
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IPC_BROKERABLE_ATTACHMENT_H_
+#define IPC_BROKERABLE_ATTACHMENT_H_
+
+#include "ipc/ipc_export.h"
+#include "ipc/ipc_message_attachment.h"
+
+namespace IPC {
+
+// An id uniquely identifies an attachment sent via a broker.
+struct IPC_EXPORT BrokerableAttachmentId {
+  uint32_t nonce[4];
+};
+
+namespace internal {
+
+// This subclass of MessageAttachment requires an AttachmentBroker to be
+// attached to a Chrome IPC message.
+class IPC_EXPORT BrokerableAttachment : public MessageAttachment {
+ public:
+  BrokerableAttachment() {}
+
+  // The identifier is unique across all Chrome processes.
+  BrokerableAttachmentId GetIdentifier() { return id_; }
+
+ protected:
+  ~BrokerableAttachment() override{};
+
+ private:
+  // This member uniquely identifier a BrokerableAttachment across all
+  // processes.
+  BrokerableAttachmentId id_;
+};
+
+}  // namespace internal
+}  // namespace IPC
+
+#endif  // IPC_BROKERABLE_ATTACHMENT_H_