[mojo] Add typemap and variant support to generators

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

Index: mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
index 4b1e658f67d733dcf9dd997eeb46bac10679ada0..c54668d211a591eb6eed816ffafaa57d34695a68 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
@@ -2,8 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-{%- set header_guard = "%s_H_"|
-        format(module.path|upper|replace("/","_")|replace(".","_")) %}
+{%- if variant -%}
+{%-   set variant_path = "%s-%s"|format(module.path, variant) -%}
+{%- else -%}
+{%-   set variant_path = module.path -%}
+{%- endif -%}
+
+{%- set header_guard = "%s_H_"|format(
+        variant_path|upper|replace("/","_")|replace(".","_")|
+            replace("-", "_")) %}
 
 #ifndef {{header_guard}}
 #define {{header_guard}}
@@ -24,7 +31,7 @@
 #include "mojo/public/cpp/bindings/no_interface.h"
 #include "mojo/public/cpp/bindings/string.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
-#include "{{module.path}}-internal.h"
+#include "{{variant_path}}-internal.h"
 {%- for import in imports %}
 #include "{{import.module.path}}.h"
 {%- endfor %}
@@ -32,6 +39,9 @@
 {%- for namespace in namespaces_as_array %}
 namespace {{namespace}} {
 {%- endfor %}
+{%- if variant %}
+namespace {{variant}} {
+{%- endif %}
 
 {#--- Enums #}
 {% from "enum_macros.tmpl" import enum_decl -%}
@@ -139,6 +149,9 @@ typedef mojo::StructPtr<{{union.name}}> {{union.name}}Ptr;
 {%-   endfor %}
 {%- endif %}
 
+{%- if variant %}
+}  // namespace {{variant}}
+{%- endif %}
 {%- for namespace in namespaces_as_array|reverse %}
 }  // namespace {{namespace}}
 {%- endfor %}