Add field-initializing constructors to generated mojo structs.

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 342 matching lines @@
   [MinVersion=3]
   string? f_string;
   [MinVersion=5]
   array<int8>? f_array;
   [MinVersion=7]
   handle<message_pipe>? f_message_pipe;
   [MinVersion=7]
   bool f_bool;
 };
 
+// A struct where the fields are not sorted by their ordinals.
+struct ReorderedStruct {
+  [MinVersion=2]
+  int32 a@3 = 3;
+  [MinVersion=4]
+  int32 b@6 = 6;
+  [MinVersion=1]
+  int32 c@1 = 1;
+};
+
 // 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;
 };
@@ skipping 22 matching lines @@
 struct ContainsHashable {
   TypemappedRect rect;
 };
 
 // Used to test that nested structs can be hashed. The nested struct mustn't be
 // nullable.
 
 struct SimpleNestedStruct {
   ContainsOther nested;
 };