Stub in more IPC attachment brokering functionality.

ipc/attachment_broker_messages.h

Index: ipc/attachment_broker_messages.h
diff --git a/ipc/attachment_broker_messages.h b/ipc/attachment_broker_messages.h
new file mode 100644
index 0000000000000000000000000000000000000000..7944c5f40dd65a1b76149405f16b8945a5d79db3
--- /dev/null
+++ b/ipc/attachment_broker_messages.h
@@ -0,0 +1,57 @@
+// 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.
+
+// IPC messages used by the attachment broker.
+// Multiply-included message file, hence no include guard.
+
+#include "ipc/brokerable_attachment.h"
+#include "ipc/ipc_message_macros.h"
+
+#if defined(OS_WIN)
+#include "ipc/handle_attachment_win.h"
+#endif  // defined(OS_WIN)
+
+// ----------------------------------------------------------------------------
+// Serialization of structs.
+// ----------------------------------------------------------------------------
+
+#if defined(OS_WIN)
+IPC_STRUCT_TRAITS_BEGIN(IPC::internal::HandleAttachmentWin::WireFormat)
+IPC_STRUCT_TRAITS_MEMBER(handle)
+IPC_STRUCT_TRAITS_MEMBER(destination_process)
+IPC_STRUCT_TRAITS_MEMBER(attachment_id)
+IPC_STRUCT_TRAITS_END()
+#endif  // defined(OS_WIN)
+
+#define IPC_MESSAGE_START AttachmentBrokerMsgStart
+
+// ----------------------------------------------------------------------------
+// Messages sent from the broker to a non-broker process.
+// ----------------------------------------------------------------------------
+
+#if defined(OS_WIN)
+// Sent from a broker to a non-broker to indicate that a windows HANDLE has been
+// brokered. Contains all information necessary for the non-broker to translate
+// a BrokerAttachment::AttachmentId to a BrokerAttachment.
+// Warning: This IPC message assumes that the sending and receiving processes

[Tom Sepez, 2015/06/19 18:04:10]

nit: the warning is true for all types in IPC -- how can a situation arise where
this wouldn't be the case?

[erikchen, 2015/06/23 22:36:59]

Chrome 32-bit Windows sometimes communicates with a 64-bit sandbox. I've updated
the WireFormat to use int32_t instead of HANDLE.

+// have the same type for HANDLE.
+IPC_MESSAGE_CONTROL1(
+    AttachmentBrokerMsg_WinHandleHasBeenBrokered,
+    IPC::internal::HandleAttachmentWin::WireFormat /* wire_format */)
+#endif  // defined(OS_WIN)
+
+// ----------------------------------------------------------------------------
+// Messages sent from a non-broker process to a broker process.
+// ----------------------------------------------------------------------------
+
+#if defined(OS_WIN)
+// Sent from a non-broker to a broker to request the duplication of a HANDLE
+// into a different process (possibly the broker process, or even the original
+// process).
+// Warning: This IPC message assumes that the sending and receiving processes
+// have the same type for HANDLE.
+IPC_MESSAGE_CONTROL1(
+    AttachmentBrokerMsg_RequestBrokerageOfWinHandle,

[Tom Sepez, 2015/06/19 18:04:10]

nit: I think you want |brokering|, the gerund form of the verb, with a brokerage
being a house of brokers (Don't throw stuff at me even though I deserve it).  Or
just BrokerWinHandle.

Or maybe DuplicateWinHandle/WinHandleHasBeenDuplicated, to get rid of the
redundant "broker" in the name, and in case brokers can do other things besides
duplicate in the future.

[erikchen, 2015/06/23 22:36:59]

I went with your suggestion of DuplicateWinHandle and
WinHandleHasBeenDuplicated.

+    IPC::internal::HandleAttachmentWin::WireFormat /* wire_format */)
+#endif  // defined(OS_WIN)