Add helper script that runs chromium.

The feature that we were previously using in chromium_headless v110 and
earlier seems to have been removed in v111. This changes the code
to use puppeteer-core to interact with chromium.

This change is intended to be a drop in replacement: The portal_settings
config that specifies the path to chromium is still used and we package the
puppeteer code so no need for post install steps.

background_scripts/chrome-helper/.eslintrc.json

@@ -0,0 +1,14 @@
+{
+  "env": {
+    "node": true
+  },
+  "parserOptions": {
+      "ecmaVersion": 2018
+  },
+  "rules": {
+      "no-console": "off"
+  },
+  "globals": {
+      "document": "readonly"
+  }
+}

background_scripts/chrome-helper/chrome-helper.js

@@ -0,0 +1,28 @@
+#!/usr/bin/env node
+const puppeteer = require('puppeteer-core');
+const args = require('yargs').argv;
+
+(async () => {
+    const browser = await puppeteer.launch({
+        executablePath: args['path-to-chrome'],
+        args: ['--no-sandbox', '--disable-extensions', '--disable-setuid-sandbox']
+    });
+    const page = await browser.newPage();
+
+    if (args['window-size']) {
+        let dimensions = args['window-size'].split(',');
+        await page.setViewport({
+            width: parseInt(dimensions[0], 10),
+            height: parseInt(dimensions[1], 10),
+            deviceScaleFactor: 1
+        });
+    }
+
+    await page.goto('file://' + args['input-file']);
+
+    const innerHtml = await page.evaluate(() => document.querySelector('.highcharts-container').innerHTML);
+
+    console.log(JSON.stringify(innerHtml));
+
+    await browser.close();
+})();