Switch 'Win x64' builder on chromium waterfall to use MB.

scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json

Index: scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json
diff --git a/scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json b/scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json
index 042760ade8d59d05209ff493ba0b3210f81653be..20086a4bdc02dd29723d1e6f1fd4d2f12dab396b 100644
--- a/scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json
+++ b/scripts/slave/recipes/chromium_trybot.expected/full_tryserver_chromium_win_win_x64_archive.json
@@ -223,6 +223,7 @@
     "cwd": "[BUILDER_CACHE]\\win_x64_archive\\src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json",
+      "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[CACHE]\\cipd\\goma' linux_dump_symbols=0 target_arch=x64 test_isolation_mode=noop use_goma=1",
       "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
@@ -353,6 +354,28 @@
     "cmd": [
       "python",
       "-u",
+      "[BUILDER_CACHE]\\win_x64_archive\\src\\tools\\mb\\mb.py",
+      "gen",
+      "-m",
+      "tryserver.chromium.win",
+      "-b",
+      "win_x64_archive",
+      "--config-file",
+      "[BUILDER_CACHE]\\win_x64_archive\\src\\tools\\mb\\mb_config.pyl",
+      "--goma-dir",
+      "[CACHE]\\cipd\\goma",
+      "//out/Release_x64"
+    ],
+    "cwd": "[BUILDER_CACHE]\\win_x64_archive\\src",
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "C:\\creds\\service_accounts\\service-account-goma-client.json"
+    },
+    "name": "generate_build_files (with patch)"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
       "RECIPE_PACKAGE_REPO[build]\\scripts\\tools\\runit.py",
       "--show-path",
       "python",