Add an option for fetching devtools from source, and a script to build the app

Change-Id: If76e4374c3ab073db778e01015d3bcbdcef3febd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/434020
Commit-Queue: Samuel Rawlins <[email protected]>
Reviewed-by: Ivan Inozemtsev <[email protected]>
Reviewed-by: Kenzie Davisson <[email protected]>

Author: srawlins

DEPS

@@ -101,6 +101,8 @@ vars = {
   "browser-compat-data_tag": "ac8cae697014da1ff7124fba33b0b4245cc6cd1b", # v1.0.22
   "cpu_features_rev": "936b9ab5515dead115606559502e3864958f7f6e",
   "devtools_rev": "53b9620798ff824f016add0fa6c25e9cc399ea0b",
+  # Use the SHA found in `flutter-candidate.txt` in the devtools repo.
+  "flutter_rev": "36ea2bdeab611e908967b6fa57659998f600a2cb",
   "icu_rev": "43953f57b037778a1b8005564afabe214834f7bd",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",
   "libcxx_rev": "bd557f6f764d1e40b62528a13b124ce740624f8f",
@@ -169,10 +171,12 @@ vars = {
   "download_emscripten": False,
   "emsdk_rev": "e41b8c68a248da5f18ebd03bd0420953945d52ff",
   "emsdk_ver": "3.1.3",
+  "build_devtools_from_sources": False,
 }
 
 gclient_gn_args_file = Var("dart_root") + '/build/config/gclient_args.gni'
 gclient_gn_args = [
+  "build_devtools_from_sources"
 ]
 
 deps = {
@@ -251,6 +255,11 @@ deps = {
       }],
       "dep_type": "cipd",
   },
+  Var("dart_root") + "/third_party/devtools_src": {
+      "url": Var("dart_git") + "external/github.com/flutter/devtools.git" +
+      "@" + Var("devtools_rev"),
+      "condition": "build_devtools_from_sources",
+  },
   Var("dart_root") + "/tests/co19/src": {
       "packages": [{
           "package": "dart/third_party/co19",
@@ -297,6 +306,12 @@ deps = {
       Var("dart_git") + "external/github.com/emscripten-core/emsdk.git" +
       "@" + Var("emsdk_rev"),
 
+  Var("dart_root") + "/third_party/flutter": {
+      "url": Var("dart_git") + "external/github.com/flutter/flutter.git" +
+      "@" + Var("flutter_rev"),
+      "condition": "build_devtools_from_sources",
+  },
+
   Var("dart_root") + "/third_party/jinja2":
       Var("chromium_git") + "/chromium/src/third_party/jinja2.git" +
       "@" + Var("jinja2_rev"),

tools/build_devtools.dart

@@ -0,0 +1,63 @@
+#!/usr/bin/env dart
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:io';
+
+import 'package:path/path.dart' as path;
+
+// Builds the Flutter DevTools app from source.
+void main() {
+  final flutterSdk = path.absolute('third_party', 'flutter', 'bin', 'flutter');
+  if (!File(flutterSdk).existsSync()) {
+    stderr.writeln('Missing Flutter SDK at "$flutterSdk"; '
+        'make sure that "../.client" has a `custom_vars` section with '
+        '`"build_devtools_from_sources": True,` and then run `gclient sync`');
+    exitCode = 1;
+    return;
+  }
+
+  final devtoolsDir = path.absolute('third_party', 'devtools_src');
+  if (!Directory(devtoolsDir).existsSync()) {
+    stderr.writeln('Missing devtools dir in devtools sources "$devtoolsDir"; '
+        'make sure that "../.client" has a `custom_vars` section with '
+        '`"build_devtools_from_sources": True,` and then run `gclient sync`');
+    exitCode = 1;
+    return;
+  }
+
+  final dtPath = path.absolute(devtoolsDir, 'tool', 'bin', 'dt.dart');
+  final buildResult = Process.runSync(
+    Platform.resolvedExecutable,
+    [dtPath, '--flutter-sdk-path=$flutterSdk', 'build'],
+    workingDirectory: devtoolsDir,
+  );
+  if (buildResult.exitCode != 0) {
+    stderr.writeln(
+        '\'${Platform.resolvedExecutable} $dtPath --flutter-sdk-path=$flutterSdk '
+        'build\' failed: exit code ${buildResult.exitCode}');
+    stderr.writeln('stdout: >>>${buildResult.stdout}<<<');
+    stderr.writeln('stderr: >>>${buildResult.stderr}<<<');
+    exitCode = 1;
+    return;
+  }
+
+  // One final check.
+  final buildDir = path.absolute('third_party', 'devtools_src', 'packages',
+      'devtools_app', 'build', 'web');
+  final mainJs = path.absolute(buildDir, 'main.dart.js');
+  final mainWasm = path.absolute(buildDir, 'main.dart.wasm');
+  if (!File(mainJs).existsSync()) {
+    stderr.writeln('Missing expected built JS app at "$mainJs"');
+    exitCode = 1;
+    return;
+  }
+  if (!File(mainWasm).existsSync()) {
+    stderr.writeln('Missing expected built WASM app at "$mainWasm"');
+    exitCode = 1;
+    return;
+  }
+
+  // Otherwise, this script is silent.
+}