Add support for dispatch contexts on BindingSet

mojo/public/cpp/bindings/associated_binding_set.h

Index: mojo/public/cpp/bindings/associated_binding_set.h
diff --git a/mojo/public/cpp/bindings/associated_binding_set.h b/mojo/public/cpp/bindings/associated_binding_set.h
new file mode 100644
index 0000000000000000000000000000000000000000..b15022358eea9bd4bde4ae92a1f4028951840d1a
--- /dev/null
+++ b/mojo/public/cpp/bindings/associated_binding_set.h
@@ -0,0 +1,27 @@
+// Copyright 2016 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.
+
+#ifndef MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_BINDING_SET_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_BINDING_SET_H_
+
+#include "mojo/public/cpp/bindings/associated_binding.h"
+#include "mojo/public/cpp/bindings/associated_interface_ptr.h"
+#include "mojo/public/cpp/bindings/associated_interface_request.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+
+namespace mojo {
+
+template <typename Interface>
+struct BindingSetTraits<AssociatedBinding<Interface>> {
+  using ProxyType = AssociatedInterfacePtr<Interface>;
+  using RequestType = AssociatedInterfaceRequest<Interface>;
+};
+
+template <typename Interface>
+using AssociatedBindingSet =
+    BindingSet<Interface, AssociatedBinding<Interface>>;
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_BINDING_SET_H_