arc-bridge: Add IPC message definitions

chromeos/arc/bridge/common/arc_instance_messages.h

Index: chromeos/arc/bridge/common/arc_instance_messages.h
diff --git a/chromeos/arc/bridge/common/arc_instance_messages.h b/chromeos/arc/bridge/common/arc_instance_messages.h
new file mode 100644
index 0000000000000000000000000000000000000000..607718d12842306f1cdc1f27b0b3cd95471719ce
--- /dev/null
+++ b/chromeos/arc/bridge/common/arc_instance_messages.h
@@ -0,0 +1,24 @@
+// 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.
+
+// Messages sent from the ARC instance to the host
+// Multiply-included message file, hence no include guard.
+
+#include <stdint.h>
+
+#include "base/file_descriptor_posix.h"
+#include "ipc/ipc_message_macros.h"
+
+#define IPC_MESSAGE_START ArcInstanceMsgStart
+
+// Registers a virtual input device on the container side.
+// |name| is the device name, like "Chrome OS Keyboard".
+// |device_type| is the device type, like "keyboard".
+// The virtual device will be reading 'struct input_event's from |fd|.  The
+// ownership of |fd| will be transferred to the receiver, so the sender must
+// not close it.
+IPC_MESSAGE_CONTROL3(ArcInstanceMsg_RegisterInputDevice,
+                     std::string, /* name */
+                     std::string, /* device_type */
+                     base::FileDescriptor /* fd */)

[dcheng, 2015/11/04 00:06:26]

I know this is the only way to send FDs across IPC today, but would you be open
to using ScopedFD once I land ParamTraits for that?

base::FileDescriptor is a class that I'd really like to get rid of.

[lhc(google), 2015/11/04 03:00:28]

Totally. Just let me know once that is landed and I'll make the change.

[Luis Héctor Chávez, 2015/11/04 16:40:58]

Rather, I want to land this as soon as possible since there are a few changes
that the whole team depends on that require this. Once that's done, I'm willing
to come back and change it with ScopedFD.

[dcheng, 2015/11/05 01:11:30]

That's fine.