Add a flag to dump IPC messages sent from the renderer to the browser.

chrome/common/external_ipc_dumper.h

Index: chrome/common/external_ipc_dumper.h
diff --git a/chrome/common/external_ipc_dumper.h b/chrome/common/external_ipc_dumper.h
new file mode 100644
index 0000000000000000000000000000000000000000..4bd69e13754afe3408a19d429ae1cb06d1a935fd
--- /dev/null
+++ b/chrome/common/external_ipc_dumper.h
@@ -0,0 +1,13 @@
+// Copyright (c) 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 CHROME_COMMON_EXTERNAL_IPC_DUMPER_H_
+#define CHROME_COMMON_EXTERNAL_IPC_DUMPER_H_
+
+#include "ipc/ipc_channel_proxy.h"
+
+IPC::ChannelProxy::OutgoingMessageFilter* LoadExternalIPCDumper(
+    base::FilePath& dump_directory);
+
+#endif  // CHROME_COMMON_EXTERNAL_IPC_DUMPER_H_