Allow Mojo structs as map keys

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 108 matching lines @@
   map<uint8, uint8> f2;
   map<int16, int16> f3;
   map<uint16, uint16> f4;
   map<int32, int32> f5;
   map<uint32, uint32> f6;
   map<int64, int64> f7;
   map<uint64, uint64> f8;
   map<float, float> f9;
   map<double, double> f10;
   map<string, string> f11;
+  // TODO(tibell): JS/Java don't support struct as key.
+  // map<Rect, Rect> f12;
 };
 
 // Used to verify that various map value types can be encoded and decoded
 // successfully.
 
 struct MapValueTypes {
   map<string, array<string>> f0;
   map<string, array<string>?> f1;
   map<string, array<string?>> f2;
   map<string, array<string, 2>> f3;
@@ skipping 240 matching lines @@
 
 struct ContainsInterfaceRequest {
   SomeInterface& request;
 };
 
 // Used to verify that boolean fields are correctly serialized/deserialized.
 
 struct SingleBoolStruct {
   bool value;
 };
+
+// Used to verify that structs containing typemapped types can be hashed (if the
+// typemapped type itself is hashable).
+
+struct ContainsHashable {
+  TypemappedRect rect;
+};