Support custom message filtering on Mojo binding objects

mojo/public/cpp/bindings/lib/router.h

Index: mojo/public/cpp/bindings/lib/router.h
diff --git a/mojo/public/cpp/bindings/lib/router.h b/mojo/public/cpp/bindings/lib/router.h
index ff6d8b90d5340af45c7b6efc9e6519ec920531ce..17286ae6f40297f6e42c9f5a50fe8bc2b4f99a73 100644
--- a/mojo/public/cpp/bindings/lib/router.h
+++ b/mojo/public/cpp/bindings/lib/router.h
@@ -18,7 +18,8 @@
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/public/cpp/bindings/connector.h"
-#include "mojo/public/cpp/bindings/lib/filter_chain.h"
+#include "mojo/public/cpp/bindings/filter_chain.h"
+#include "mojo/public/cpp/bindings/message.h"
 
 namespace mojo {
 namespace internal {
@@ -58,6 +59,8 @@ class Router : public MessageReceiverWithResponder {
     return connector_.is_valid();
   }
 
+  void AddFilter(std::unique_ptr<MessageReceiver> filter);
+
   // Please note that this method shouldn't be called unless it results from an
   // explicit request of the user of bindings (e.g., the user sets an
   // InterfacePtr to null or closes a Binding).