misc: support --chrome-flags in run devtools script

.github/workflows/devtools.yml

@@ -152,6 +152,11 @@ jobs:
     - run: yarn --frozen-lockfile --network-timeout 1000000
       working-directory: ${{ github.workspace }}/lighthouse
 
+    # This is only done because the import of `parseChromeFlags` in pptr-run-devtool.js triggers imports that eventually
+    # fail because of how report-assets.js reads generated files.
+    - run: yarn build-report
+      working-directory: ${{ github.workspace }}/lighthouse
+
     - name: Define ToT chrome path
       run: echo "CHROME_PATH=/Users/runner/chrome-mac-tot/Chromium.app/Contents/MacOS/Chromium" >> $GITHUB_ENV
     - name: Install Chrome ToT

lighthouse-cli/test/smokehouse/lighthouse-runners/devtools.js

@@ -75,10 +75,13 @@ async function runLighthouse(url, configJson, testRunnerOptions = {}) {
   await buildDevtoolsPromise;
 
   const outputDir = fs.mkdtempSync(os.tmpdir() + '/lh-smoke-cdt-runner-');
+  const chromeFlags = [
+    `--custom-devtools-frontend=file://${devtoolsDir}/out/Default/gen/front_end`,
+  ];
   const args = [
     'run-devtools',
     url,
-    `--custom-devtools-frontend=file://${devtoolsDir}/out/Default/gen/front_end`,
+    `--chrome-flags=${chromeFlags.join(' ')}`,
     '--output-dir', outputDir,
   ];
   if (configJson) {

lighthouse-core/scripts/pptr-run-devtools.js

@@ -12,11 +12,11 @@
  *
  * To use with locally built DevTools and Lighthouse, run (assuming devtools at ~/src/devtools/devtools-frontend):
  *    yarn devtools
- *    yarn run-devtools --custom-devtools-frontend=file://$HOME/src/devtools/devtools-frontend/out/Default/gen/front_end
+ *    yarn run-devtools --chrome-flags=--custom-devtools-frontend=file://$HOME/src/devtools/devtools-frontend/out/Default/gen/front_end
  *
  * Or with the DevTools in .tmp:
  *   bash lighthouse-core/test/chromium-web-tests/setup.sh
- *   yarn run-devtools --custom-devtools-frontend=file://$PWD/.tmp/chromium-web-tests/devtools/devtools-frontend/out/Default/gen/front_end
+ *   yarn run-devtools --chrome-flags=--custom-devtools-frontend=file://$PWD/.tmp/chromium-web-tests/devtools/devtools-frontend/out/Default/gen/front_end
  *
  * URL list file: yarn run-devtools < path/to/urls.txt
  * Single URL: yarn run-devtools "https://example.com"
@@ -30,6 +30,8 @@ import puppeteer from 'puppeteer';
 import yargs from 'yargs';
 import * as yargsHelpers from 'yargs/helpers';
 
+import {parseChromeFlags} from '../../lighthouse-cli/run.js';
+
 const y = yargs(yargsHelpers.hideBin(process.argv));
 const argv_ = y
   .usage('$0 [url]')
@@ -40,9 +42,9 @@ const argv_ = y
     default: 'latest-run/devtools-lhrs',
     alias: 'o',
   })
-  .option('custom-devtools-frontend', {
+  .option('chrome-flags', {
     type: 'string',
-    alias: 'd',
+    default: '',
   })
   .option('config', {
     type: 'string',
@@ -287,6 +289,7 @@ async function readUrlList() {
 }
 
 async function run() {
+  const chromeFlags = parseChromeFlags(argv['chromeFlags']);
   const outputDir = argv['output-dir'];
 
   // Create output directory.
@@ -299,7 +302,9 @@ async function run() {
     fs.mkdirSync(outputDir);
   }
 
-  const customDevtools = argv['custom-devtools-frontend'];
+  const customDevtools = chromeFlags
+    .find(f => f.startsWith('--custom-devtools-frontend='))
+    ?.replace('--custom-devtools-frontend=', '');
   if (customDevtools) {
     console.log(`Using custom devtools frontend: ${customDevtools}`);
     console.log('Make sure it has been built recently!');
@@ -313,7 +318,7 @@ async function run() {
 
   const browser = await puppeteer.launch({
     executablePath: process.env.CHROME_PATH,
-    args: customDevtools ? [`--custom-devtools-frontend=${customDevtools}`] : [],
+    args: chromeFlags,
     devtools: true,
   });