Example of how to interpose yourself in a message stream.

content/common/set_ipc_fuzzing.cc

+// Copyright (c) 2011 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.
+
+#include "content/common/set_ipc_fuzzing.h"
+
+#if defined(OS_LINUX)
+#include <dlfcn.h>
+#endif
+
+typedef IPC::SyncChannel::OutgoingMessageFilter *(*GetFuzzerFunction)();
+const char kFuzzLibraryName[] = "libipcfuzz.so";
+const char kFuzzEntryPointName[] = "GetFilter";
+
+void SetIPCFuzzing(IPC::SyncChannel *channel) {
+
+#if defined(OS_LINUX)
+  // Fuzz is currently linux-only feature
+  void *fuzz_library =  dlopen(kFuzzLibraryName, RTLD_LAZY);
+  if (fuzz_library) {
+    GetFuzzerFunction fuzz_entry_point = reinterpret_cast<GetFuzzerFunction>(
+        dlsym(fuzz_library, kFuzzEntryPointName));
+
+    if (fuzz_entry_point)
+      channel->set_outgoing_message_filter(fuzz_entry_point());
+  }
+#endif // OS_LINUX
+
+}
+
+
+