beginnings of metro viewer process

ui/viewer/viewer_messages.h

Index: ui/viewer/viewer_messages.h
diff --git a/ui/viewer/viewer_messages.h b/ui/viewer/viewer_messages.h
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+++ b/ui/viewer/viewer_messages.h
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+// Copyright (c) 2012 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.
+
+// Multiply-included message file, no traditional include guard.
+#include <string>
+
+#include "ipc/ipc_channel_handle.h"
+#include "ipc/ipc_message_macros.h"
+
+#define IPC_MESSAGE_START ViewerMsgStart
+
+//-----------------------------------------------------------------------------
+// Viewer process messages:
+// These are messages from the browser to the viewer process.
+
+// Shares the rendering handle to the viewer process.
+IPC_MESSAGE_CONTROL1(ViewerMsg_PbufferHandle,
+                     std::string /* TODO(scottmg): whatever type */)
+
+//-----------------------------------------------------------------------------
+// Viewer process host messages:
+// These are messages from the viewer process to the browser.
+
+// Connect to the browser (request a pbuffer handle).
+IPC_MESSAGE_CONTROL0(ViewerHostMsg_Connect)