libyuv: Switch bots over to GN by default.

scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json

Index: scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json
diff --git a/scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json b/scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json
index 050600bd612ea89986e540d56058d761f35ffb74..b66076dd32d61929f884421952dad1fccaaebdf7 100644
--- a/scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json
+++ b/scripts/slave/recipes/libyuv/libyuv.expected/tryserver_libyuv_android_x64.json
@@ -134,6 +134,7 @@
     "cwd": "[SLAVE_BUILD]/src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
+      "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_CROSSCOMPILE": "1",
       "GYP_DEFINES": "OS=android component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[CACHE]/cipd/goma' target_arch=x64 use_goma=1",
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
@@ -144,6 +145,19 @@
     "cmd": [
       "python",
       "-u",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gn.py",
+      "--root=[SLAVE_BUILD]/src",
+      "gen",
+      "//out/Debug",
+      "--args=is_component_build=false symbol_level=2 dcheck_always_on=true is_debug=true target_os=\"android\" target_cpu=\"x64\" use_goma=true goma_dir=\"[CACHE]/cipd/goma\""
+    ],
+    "cwd": "[SLAVE_BUILD]/src",
+    "name": "gn"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py",
       "--show-path",
       "python",