WebRTC: Enable MB on our remaining Chromium builders.

scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Linux_Builder.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "chromium.webrtc",
       "--builder",
       "Linux Builder",
@@ skipping 166 matching lines @@
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]/src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
+      "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "blink_logging_always_on=1 component=static_library dcheck_always_on=1 ffmpeg_branding=Chrome gomadir='[CACHE]/cipd/goma' proprietary_codecs=1 target_arch=x64 use_goma=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/testing/scripts/get_compile_targets.py",
@@ skipping 36 matching lines @@
       "--show-path",
       "python",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/cleanup_temp.py"
     ],
     "name": "cleanup_temp"
   },
   {
     "cmd": [
       "python",
       "-u",
+      "[SLAVE_BUILD]/src/tools/mb/mb.py",
+      "gen",
+      "-m",
+      "chromium.webrtc",
+      "-b",
+      "Linux Builder",
+      "--config-file",
+      "[SLAVE_BUILD]/src/tools/mb/mb_config.pyl",
+      "--goma-dir",
+      "[CACHE]/cipd/goma",
+      "//out/Release"
+    ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
+    "name": "generate_build_files"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py",
       "--show-path",
       "python",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/compile.py",
       "--gsutil-py-path",
       "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "--ninja-path",
       "RECIPE_PACKAGE_REPO[depot_tools]/ninja",
       "--target",
       "Release",
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
       "--build-tool",
       "ninja",
       "--build-data-dir",
       "[ROOT]/build_data_dir",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
       "--goma-service-account-json-file",
       "/creds/service_accounts/service-account-goma-client.json",
       "--goma-dir",
       "[CACHE]/cipd/goma",
       "--",
       "browser_tests",
-      "chromium_builder_webrtc",
       "content_browsertests",
       "content_unittests",
       "media_unittests",
       "remoting_unittests"
     ],
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "compile",
     "~followup_annotations": [
@@ skipping 54 matching lines @@
     "~followup_annotations": [
       "@@@STEP_TEXT@Linux Tester@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]