Allow Mojo structs as map keys

mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl

 // 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.
 
 {%- if variant -%}
 {%-   set variant_path = "%s-%s"|format(module.path, variant) -%}
 {%- else -%}
 {%-   set variant_path = module.path -%}
 {%- endif -%}
 
@@ skipping 51 matching lines @@
 {%-   else %}
 #include "{{import.module.path}}.h"
 {%-   endif %}
 {%- endfor %}
 {%- if not for_blink %}
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/string.h"
 {%- else %}
 #include "mojo/public/cpp/bindings/wtf_array.h"
 #include "mojo/public/cpp/bindings/wtf_map.h"
+#include "third_party/WebKit/Source/wtf/HashFunctions.h"
 #include "third_party/WebKit/Source/wtf/Optional.h"
 #include "third_party/WebKit/Source/wtf/text/WTFString.h"
 {%- endif %}
 
 {%- for header in extra_public_headers %}
 #include "{{header}}"
 {%- endfor %}
 
 {%- if export_header %}
 #include "{{export_header}}"
@@ skipping 131 matching lines @@
 {#--- Union Serialization Helpers -#}
 {%  if unions %}
 {%-   for union in unions %}
 {%      include "union_traits_declaration.tmpl" %}
 {%-   endfor %}
 {%- endif %}
 
 }  // namespace mojo
 
 #endif  // {{header_guard}}