Reduce code size of BindingState

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

Index: mojo/public/cpp/bindings/lib/filter_chain.cc
diff --git a/mojo/public/cpp/bindings/lib/filter_chain.cc b/mojo/public/cpp/bindings/lib/filter_chain.cc
index 899bac1624a28256151558b6d121fb8b7ffc79bf..58bdbd55df27a365653ca09efe90f5be63dbc965 100644
--- a/mojo/public/cpp/bindings/lib/filter_chain.cc
+++ b/mojo/public/cpp/bindings/lib/filter_chain.cc
@@ -45,5 +45,11 @@ MessageReceiver* FilterChain::GetHead() {
   return filters_.empty() ? sink_ : filters_.front();
 }
 
+void FilterChain::Append(MessageFilter* filter) {
+  if (!filters_.empty())
+    filters_.back()->set_sink(filter);
+  filters_.push_back(filter);
+}
+
 }  // namespace internal
 }  // namespace mojo