Revert of Mojo C++ bindings: always use MultiplexRouter with InterfacePtr/Binding.

mojo/public/cpp/bindings/binding.h

Index: mojo/public/cpp/bindings/binding.h
diff --git a/mojo/public/cpp/bindings/binding.h b/mojo/public/cpp/bindings/binding.h
index 71257d2ac420d589d1ddd84854ba0f8539203baa..7784afb5501580143ad50f73d714d26bd242112c 100644
--- a/mojo/public/cpp/bindings/binding.h
+++ b/mojo/public/cpp/bindings/binding.h
@@ -271,7 +271,8 @@
   void EnableTestingMode() { internal_state_.EnableTestingMode(); }
 
  private:
-  internal::BindingState<Interface, true> internal_state_;
+  internal::BindingState<Interface, Interface::PassesAssociatedKinds_>
+      internal_state_;
 
   DISALLOW_COPY_AND_ASSIGN(Binding);
 };