Use MB on all of the blink bots.

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

Index: scripts/slave/recipes/chromium_trybot.expected/webkit_tests_unexpected_error.json
diff --git a/scripts/slave/recipes/chromium_trybot.expected/webkit_tests_unexpected_error.json b/scripts/slave/recipes/chromium_trybot.expected/webkit_tests_unexpected_error.json
index 2e339d02f07ed85fad1bcc64101b45bf041b16ce..8a7c80435275ffd4c231077a88eab9b021532c85 100644
--- a/scripts/slave/recipes/chromium_trybot.expected/webkit_tests_unexpected_error.json
+++ b/scripts/slave/recipes/chromium_trybot.expected/webkit_tests_unexpected_error.json
@@ -119,6 +119,7 @@
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
+      "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]/goma' target_arch=x64 test_isolation_mode=prepare use_goma=1"
     },
     "name": "gclient runhooks (with patch)"
@@ -244,6 +245,25 @@
     "cmd": [
       "python",
       "-u",
+      "[SLAVE_BUILD]/src/tools/mb/mb.py",
+      "gen",
+      "-m",
+      "tryserver.blink",
+      "-b",
+      "linux_blink_rel",
+      "--config-file",
+      "[SLAVE_BUILD]/src/tools/mb/mb_config.pyl",
+      "--goma-dir",
+      "[BUILD]/goma",
+      "//out/Release"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "generate_build_files (with patch)"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
       "[BUILD]/scripts/slave/compile.py",
       "--target",
       "Release",