Interfaces declared first in header file.

mojo/public/interfaces/bindings/tests/test_structs.mojom

 // Copyright 2013 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.
 
 [JavaPackage="org.chromium.mojo.bindings.test.mojom.test_structs"]
 module mojo.test;
 
 import "mojo/public/interfaces/bindings/tests/rect.mojom";
 
 struct NamedRegion {
@@ skipping 334 matching lines @@
   Rect? f_rect;
   [MinVersion=3]
   string? f_string;
   [MinVersion=5]
   array<int8>? f_array;
   [MinVersion=7]
   handle<message_pipe>? f_message_pipe;
   [MinVersion=7]
   bool f_bool;
 };
+
+// Used to verify that interfaces that are struct members can be defined in the
+// same file.
+
+interface SomeInterface {
+  SomeMethod(RectPair pair) => (RectPair other_pair);
+};
+
+struct ContainsInterface {
+  SomeInterface some_interface;
+};