Add recipe config for android clang x86 tester.

scripts/slave/recipe_modules/chromium_android/config.py

 # 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.
 
 import types
 
 from recipe_engine.config import config_item_context, ConfigGroup
 from recipe_engine.config import ConfigList, Dict, List, Single, Static
 from recipe_engine.config_types import Path
 
@@ skipping 66 matching lines @@
 
 @config_ctx(config_vars={'BUILD_CONFIG': 'Release'})
 def clang_asan_tot_release_builder(c):  # pragma: no cover
   c.asan_symbolize = True
   c.env.LLVM_FORCE_HEAD_REVISION = 'YES'
 
 @config_ctx(config_vars={'BUILD_CONFIG': 'Debug'})
 def clang_tot_debug_builder(c):  # pragma: no cover
   c.env.LLVM_FORCE_HEAD_REVISION = 'YES'
 
+@config_ctx(includes=['x64_builder_mb'])
+def clang_builder_mb_x64(c):
+  pass
+
 @config_ctx()
 def x86_base(c):
   pass
 
 @config_ctx(includes=['x86_base'])
 def x86_builder(c):
   pass
 
 @config_ctx(includes=['x86_builder'])
 def x86_builder_mb(c):
@@ skipping 134 matching lines @@
 def cast_builder(c):
   pass
 
 @config_ctx()
 def restart_usb(c):
   c.restart_usb = True
 
 @config_ctx()
 def use_devil_adb(c):
   c.use_devil_adb = True