Mojo: Change the blink variant from "wtf" to "blink".

device/usb/usb.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'mojom_files': [
       'public/interfaces/chooser_service.mojom',
       'public/interfaces/device.mojom',
@@ skipping 138 matching lines @@
       'sources': [ '<@(mojom_files)' ],
       'includes': [
         '../../mojo/mojom_bindings_generator.gypi',
       ],
     },
     {
       'target_name': 'device_usb_mojo_bindings_for_blink',
       'type': 'static_library',
       'sources': [ '<@(mojom_files)' ],
       'variables': {
-        'mojom_variant': 'wtf',
         'for_blink': 'true',
       },
       'includes': [
         '../../mojo/mojom_bindings_generator.gypi',
       ],
     },
     {
       'target_name': 'device_usb_mocks',
       'type': 'static_library',
       'include_dirs': [
@@ skipping 48 matching lines @@
           'type': 'none',
           'variables': {
             'source_file': 'usb_descriptors.h',
           },
           'includes': [ '../../build/android/java_cpp_enum.gypi' ],
         },
       ],
     }],
   ],
 }