add supported luci builders (#20099)

* add supported luci builders

* fix license

* add readme

* add code to validate json contents

* license

* move dev to ci

* fix license

* add shell script to run test

ci/dev/README.md

+This directory contains resources that the Flutter team uses during 
+the development of engine.
+
+## Luci builder file
+`engine_try_builders.json` and `engine_prod_builders.json` contains the 
+supported luci try/prod builders for engine. It follows format:
+```json
+{
+    "builders":[
+        {
+            "name":"xxx",
+            "repo":"engine"
+        },
+        {
+            "name":"yyy",
+            "repo":"engine"
+        }
+    ]
+}
+```
+This file will be mainly used in [`flutter/cocoon`](https://github.com/flutter/cocoon)
+to trigger/update engine luci tasks.
+
+If any new changes, please validate json contents by running
+```
+dart validate_json.dart engine_try_builders.json
+dart validate_json.dart engine_prod_builders.json
+```

ci/dev/dev_test.sh

+#!/bin/bash
+# Copyright 2020 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Runner for dart tests. It expects a single parameter with the full
+# path to the start folder where tests will be run.
+
+set -e
+
+dir=$(dirname $0)
+
+pushd $dir > /dev/null
+dart validate_json.dart engine_try_builders.json
+dart validate_json.dart engine_prod_builders.json
+
+popd > /dev/null
+
+

ci/dev/engine_prod_builders.json

+{
+   "builders":[
+      {
+         "name":"Linux Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Fuchsia",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Android AOT Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Android Debug Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Android AOT Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Android Debug Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac iOS Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac iOS Engine Profile",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac iOS Engine Release",
+         "repo":"engine"
+      },
+      {
+         "name":"Windows Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Windows Android AOT Engine",
+         "repo":"engine"
+      }
+   ]
+}

ci/dev/engine_try_builders.json

+{
+   "builders":[
+      {
+         "name":"Linux Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Fuchsia",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Android AOT Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Android Debug Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Linux Web Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Android AOT Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Android Debug Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac iOS Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Windows Host Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Windows Android AOT Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Windows Web Engine",
+         "repo":"engine"
+      },
+      {
+         "name":"Mac Web Engine",
+         "repo":"engine"
+      }
+   ]
+}

ci/dev/validate_json.dart

+// Copyright 2020 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+import 'dart:io' show File;
+import 'dart:io' as io_internals show exit;
+
+final bool hasColor = stdout.supportsAnsiEscapes;
+final String bold = hasColor ? '\x1B[1m' : ''; // used for shard titles
+final String red = hasColor ? '\x1B[31m' : ''; // used for errors
+final String reset = hasColor ? '\x1B[0m' : '';
+final String reverse = hasColor ? '\x1B[7m' : ''; // used for clocks
+
+/// Validates if the input builders JSON file has valid contents.
+///
+/// Examples:
+/// dart validate_json.dart /path/to/json/file
+Future<void> main(List<String> args) async {
+  final String jsonString = await File(args[0]).readAsString();
+  Map<String, dynamic> decodedJson;
+  final List<String> messages = <String>[];
+  try {
+    decodedJson = json.decode(jsonString) as Map<String, dynamic>;
+    final List<dynamic> builders = decodedJson['builders'] as List<dynamic>;
+    if (builders == null) {
+      messages.add('${bold}Json format is violated: no "builders" exists. Please follow: $reset');
+      messages.add('''
+      {
+        "builders":[
+          {
+            "name":"xxx",
+            "repo":"engine"
+          }, {
+            "name":"xxx",
+            "repo":"engine"
+          }
+        ]
+      }''');
+      exitWithError(messages);
+    }
+  } on ExitException catch (error) {
+    error.apply();
+  }
+  print('$clock ${bold}Analysis successful for ${args[0]}.$reset');
+}
+
+class ExitException implements Exception {
+  ExitException(this.exitCode);
+
+  final int exitCode;
+
+  void apply() {
+    io_internals.exit(exitCode);
+  }
+}
+
+void exitWithError(List<String> messages) {
+  final String redLine = '$red━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━$reset';
+  print(redLine);
+  messages.forEach(print);
+  print(redLine);
+  exit(1);
+}
+
+String get clock {
+  final DateTime now = DateTime.now();
+  return '$reverse▌'
+      '${now.hour.toString().padLeft(2, "0")}:'
+      '${now.minute.toString().padLeft(2, "0")}:'
+      '${now.second.toString().padLeft(2, "0")}'
+      '▐$reset';
+}
+
+