Mojo cpp bindings: add support for validating incoming messages.

mojo/public/cpp/bindings/lib/message_filter.cc

Index: mojo/public/cpp/bindings/lib/message_filter.cc
diff --git a/mojo/public/cpp/bindings/lib/message_filter.cc b/mojo/public/cpp/bindings/lib/message_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a5203133160cfed9e25b3292b35a50668b2d91e4
--- /dev/null
+++ b/mojo/public/cpp/bindings/lib/message_filter.cc
@@ -0,0 +1,31 @@
+// Copyright 2014 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 "mojo/public/cpp/bindings/message_filter.h"
+
+#include <assert.h>
+
+namespace mojo {
+
+MessageFilter::MessageFilter(MessageReceiver* sink) : sink_(sink) {
+}
+
+MessageFilter::~MessageFilter() {
+}
+
+bool MessageFilter::AcceptWithResponder(Message* message,
+                                        MessageReceiver* responder) {
+  assert(false);  // Not reached!
+  return false;
+}
+
+PassThroughFilter::PassThroughFilter(MessageReceiver* sink)
+    : MessageFilter(sink) {
+}
+
+bool PassThroughFilter::Accept(Message* message) {
+  return sink_->Accept(message);
+}
+
+}  // namespace mojo