Mojo C++ bindings: assume that all imported mojoms have the same variant as current mojom

mojo/mojo_public.gyp

 # Copyright 2014 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.
 
 {
   'includes': [
     'mojo_variables.gypi',
   ],
   'target_defaults' : {
     'include_dirs': [
@@ skipping 497 matching lines @@
       ],
       'includes': [ 'mojom_bindings_generator.gypi' ],
     },
     {
       'target_name': 'mojo_public_test_variant',
       'type': 'static_library',
       'variables': {
         'mojom_variant': 'test_variant',
       },
       'sources': [
+        'public/interfaces/bindings/tests/test_variant_import.mojom',
         'public/interfaces/bindings/tests/test_variant.mojom',
       ],
       'includes': [ 'mojom_bindings_generator.gypi' ],
     },
   ],
   'conditions': [
     ['OS == "android"', {
       'targets': [
         {
           # GN version: //mojo/public/java:system
@@ skipping 24 matching lines @@
              'mojo_interface_bindings_java_sources',
              'mojo_public_java',
              '<(DEPTH)/base/base.gyp:base_java',
            ],
            'includes': [ '../build/java.gypi' ],
         },
       ],
     }],
   ],
 }