Flip win_chromium_x64_rel_ng to MB, GN

scripts/slave/recipe_modules/chromium_tests/trybots.py

 # 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.
 
 from recipe_engine.types import freeze
 
 
 def simple_bot(bot_id, analyze_mode=None):
   return {
     'bot_ids': [bot_id],
@@ skipping 562 matching lines @@
       'win_chromium_compile_dbg_ng_exp': simple_bot({
         'mastername': 'chromium.win',
         'buildername': 'Win Builder (dbg)',
       }, analyze_mode='compile'),
       'win_chromium_compile_rel_ng': simple_bot({
         'mastername': 'chromium.win',
         'buildername': 'Win Builder',
       }, analyze_mode='compile'),
       'win_chromium_x64_rel_ng': simple_bot({
         'mastername': 'chromium.win',
-        'buildername': 'Win x64 Builder',
-        'tester': 'Win 7 Tests x64 (1)',
+        'buildername': 'Win x64 GN',
+        'tester': 'Win x64 GN',
       }),
       'win_chromium_x64_rel_ng_exp': simple_bot({
         'mastername': 'chromium.win',
         'buildername': 'Win x64 Builder',
         'tester': 'Win 7 Tests x64 (1)',
       }),
       'win8_chromium_ng': simple_bot({
         'mastername': 'chromium.win',
         'buildername': 'Win8 Aura',
       }),
@@ skipping 41 matching lines @@
   },
   'tryserver.v8': {
     'builders': {
       'v8_linux_blink_rel': simple_bot({
         'mastername': 'chromium.webkit',
         'buildername': 'WebKit Linux',
       }),
     },
   },
 })