Change mojo geometry structs from using type converters to StructTraits.

ui/mojo/geometry/mojo_bindings.gyp

 # Copyright 2015 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.
 
 {
   'targets': [
     {
       # GN version: //ui/mojo/geometry
       'target_name': 'mojo_geometry_bindings_mojom',
       'type': 'none',
       'variables': {
         'mojom_files': [
           'geometry.mojom',
         ],
+        'mojom_typemaps': [
+          'geometry.typemap',
+        ]
       },
       'includes': [ '../../../mojo/mojom_bindings_generator_explicit.gypi' ],
     },
     {
       'target_name': 'mojo_geometry_bindings',
       'type': 'static_library',
       'dependencies': [
         'mojo_geometry_bindings_mojom',
         '../../../mojo/mojo_public.gyp:mojo_cpp_bindings',
       ],
     },
   ],
 }