Add the MB config for the win_pgo_x64 trybot

tools/mb/mb_config.pyl

 # 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.
 
 # This is a .pyl, or "Python Literal", file. You can treat it just like a
 # .json file, with the following exceptions:
 # * all keys must be quoted (use single quotes, please);
 # * comments are allowed, using '#' syntax; and
 # * trailing commas are allowed.
 
@@ skipping 649 matching lines @@
       'win_clang_x64_dbg': 'win_clang_debug_bot',
       'win_clang_x64_rel': 'clang_official_release_trybot',
       'win_mojo': 'release_trybot_x86',
       'win_nacl_sdk': 'release_bot_x86',
       'win_nacl_sdk_build': 'release_bot_x86',
       'win_optional_gpu_tests_rel': 'gpu_tests_deqp_gles_release_trybot_x86',
       'win_pgo': {
         '1': 'official_optimize_chrome_pgo_phase_1_x86',
         '2': 'official_optimize_chrome_pgo_phase_2_x86',
       },
+      'win_pgo_x64': {
+        '1': 'official_optimize_chrome_pgo_phase_1',
+        '2': 'official_optimize_chrome_pgo_phase_2',
+      },
       'win_upload_clang': 'release_bot',
       'win_chrome_official': 'official_goma_x86',
     },
 
     'tryserver.v8': {
       'v8_android_chromium_gn_dbg': 'android_debug_bot',
       'v8_linux_blink_rel': 'release_trybot',
       'v8_linux_chromium_gn_rel': 'release_trybot',
     },
   },
@@ skipping 1235 matching lines @@
 
     'x64': {
       'gn_args': 'target_cpu="x64"',
     },
 
     'x86': {
       'gn_args': 'target_cpu="x86"',
     },
   },
 }