libyuv: Add GN bots for Win,Mac,Linux,Android

scripts/slave/recipes/libyuv/libyuv.expected/client_libyuv_mac64_debug__gn_.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "client.libyuv",
       "--builder",
-      "Mac64 Debug",
+      "Mac64 Debug (GN)",
       "--slave",
       "slavename",
       "--spec",
       "cache_dir = '[GIT_CACHE]'\nsolutions = [{'custom_vars': {'root_dir': 'src'}, 'deps_file': 'DEPS', 'managed': True, 'name': 'src', 'url': 'https://chromium.googlesource.com/libyuv/libyuv'}]",
       "--root",
       "src",
       "--revision_mapping_file",
       "{}",
       "--git-cache-dir",
       "[GIT_CACHE]",
@@ skipping 28 matching lines @@
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
+      "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "clang=1 component=shared_library gomadir='[BUILD]/goma' target_arch=x64 use_goma=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
+    "cmd": [
+      "python",
+      "-u",
+      "[DEPOT_TOOLS]/gn.py",
+      "--root=[SLAVE_BUILD]/src",
+      "gen",
+      "//out/Debug",
+      "--args=is_debug=true target_cpu=\"x64\" use_goma=true goma_dir=\"[BUILD]/goma\""
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "gn"
+  },
+  {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/clang_revision.py",
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--output-json",
       "/path/to/tmp/json"
     ],
@@ skipping 24 matching lines @@
       "[GOMA_CACHE]",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma-clang",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
-      "All"
+      "all"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "compile",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Debug",
       "--factory-properties",
-      "{\"BUILD_CONFIG\": \"Debug\", \"buildername\": \"Mac64 Debug\", \"mastername\": \"client.libyuv\", \"recipe\": \"libyuv/libyuv\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
+      "{\"BUILD_CONFIG\": \"Debug\", \"buildername\": \"Mac64 Debug (GN)\", \"mastername\": \"client.libyuv\", \"recipe\": \"libyuv/libyuv\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--build-properties",
-      "{\"BUILD_CONFIG\": \"Debug\", \"buildername\": \"Mac64 Debug\", \"mastername\": \"client.libyuv\", \"recipe\": \"libyuv/libyuv\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
+      "{\"BUILD_CONFIG\": \"Debug\", \"buildername\": \"Mac64 Debug (GN)\", \"mastername\": \"client.libyuv\", \"recipe\": \"libyuv/libyuv\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--step-name=libyuv_unittest",
-      "--builder-name=Mac64 Debug",
+      "--builder-name=Mac64 Debug (GN)",
       "--slave-name=slavename",
       "libyuv_unittest"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "libyuv_unittest"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]