feat: introduce puppeteer-firefox (#3628)

This adds a proof-of-concept of `puppeteer-firefox`.
This consists of two parts:
- `//experimental/juggler` - patches to apply to Firefox.
- `//experimental/puppeteer-firefox` - front-end code to
be merged with Puppeteer.

As things become more stable, we'll gradually move it out of
the experimental folder.

experimental/puppeteer-firefox/install.js

@@ -0,0 +1,153 @@
+/**
+ * Copyright 2018 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+const os = require('os');
+const fs = require('fs');
+const path = require('path');
+
+// puppeteer-core should not install anything.
+if (require('./package.json').name === 'puppeteer-core')
+  return;
+
+const downloadHost = process.env.PUPPETEER_DOWNLOAD_HOST || process.env.npm_config_puppeteer_download_host || process.env.npm_package_config_puppeteer_download_host;
+
+const puppeteer = require('./index');
+const browserFetcher = puppeteer.createBrowserFetcher({ host: downloadHost, product: 'firefox' });
+
+const revision = require('./package.json').puppeteer.firefox_revision;
+
+const revisionInfo = browserFetcher.revisionInfo(revision);
+
+// Do nothing if the revision is already downloaded.
+if (revisionInfo.local)
+  return;
+
+// Override current environment proxy settings with npm configuration, if any.
+const NPM_HTTPS_PROXY = process.env.npm_config_https_proxy || process.env.npm_config_proxy;
+const NPM_HTTP_PROXY = process.env.npm_config_http_proxy || process.env.npm_config_proxy;
+const NPM_NO_PROXY = process.env.npm_config_no_proxy;
+
+if (NPM_HTTPS_PROXY)
+  process.env.HTTPS_PROXY = NPM_HTTPS_PROXY;
+if (NPM_HTTP_PROXY)
+  process.env.HTTP_PROXY = NPM_HTTP_PROXY;
+if (NPM_NO_PROXY)
+  process.env.NO_PROXY = NPM_NO_PROXY;
+
+browserFetcher.download(revisionInfo.revision, onProgress)
+    .then(() => browserFetcher.localRevisions())
+    .then(onSuccess)
+    .catch(onError);
+
+/**
+ * @param {!Array<string>}
+ * @return {!Promise}
+ */
+function onSuccess(localRevisions) {
+  console.log('Firefox downloaded to ' + revisionInfo.folderPath);
+  localRevisions = localRevisions.filter(revision => revision !== revisionInfo.revision);
+  // Remove previous firefox revisions.
+  const cleanupOldVersions = localRevisions.map(revision => browserFetcher.remove(revision));
+  return Promise.all([...cleanupOldVersions, installFirefoxPreferences()]);
+}
+
+/**
+ * @param {!Error} error
+ */
+function onError(error) {
+  console.error(`ERROR: Failed to download Firefox r${revision}!`);
+  console.error(error);
+  process.exit(1);
+}
+
+let progressBar = null;
+let lastDownloadedBytes = 0;
+function onProgress(downloadedBytes, totalBytes) {
+  if (!progressBar) {
+    const ProgressBar = require('progress');
+    progressBar = new ProgressBar(`Downloading Firefox+Puppeteer ${revision.substring(0, 8)} - ${toMegabytes(totalBytes)} [:bar] :percent :etas `, {
+      complete: '|',
+      incomplete: ' ',
+      width: 20,
+      total: totalBytes,
+    });
+  }
+  const delta = downloadedBytes - lastDownloadedBytes;
+  lastDownloadedBytes = downloadedBytes;
+  progressBar.tick(delta);
+}
+
+function toMegabytes(bytes) {
+  const mb = bytes / 1024 / 1024;
+  return `${Math.round(mb * 10) / 10} Mb`;
+}
+
+// Install browser preferences after downloading and unpacking
+// firefox instances.
+// Based on:   https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Enterprise_deployment_before_60#Configuration
+async function installFirefoxPreferences() {
+  const revisionInfo = browserFetcher.revisionInfo(revision);
+  const firefoxFolder = path.dirname(revisionInfo.executablePath);
+  const {helper} = require('./lib/firefox/helper');
+  const mkdirAsync = helper.promisify(fs.mkdir.bind(fs));
+
+  let prefPath = '';
+  let configPath = '';
+  if (os.platform() === 'darwin') {
+    prefPath = path.join(firefoxFolder, '..', 'Resources', 'defaults', 'pref');
+    configPath = path.join(firefoxFolder, '..', 'Resources');
+  } else if (os.platform() === 'linux') {
+    await mkdirAsync(path.join(firefoxFolder, 'browser', 'defaults'));
+    await mkdirAsync(path.join(firefoxFolder, 'browser', 'defaults', 'preferences'));
+    prefPath = path.join(firefoxFolder, 'browser', 'defaults', 'preferences');
+    configPath = firefoxFolder;
+  } else if (os.platform() === 'win32') {
+    prefPath = path.join(firefoxFolder, 'defaults', 'pref');
+    configPath = firefoxFolder;
+  } else {
+    throw new Error('Unsupported platform: ' + os.platform());
+  }
+
+  await Promise.all([
+    copyFile({
+      from: path.join(__dirname, 'misc', '00-puppeteer-prefs.js'),
+      to: path.join(prefPath, '00-puppeteer-prefs.js'),
+    }),
+    copyFile({
+      from: path.join(__dirname, 'misc', 'puppeteer.cfg'),
+      to: path.join(configPath, 'puppeteer.cfg'),
+    }),
+  ]).then(() => {
+    console.log('Firefox preferences installed!');
+  });
+}
+
+function copyFile({from, to}) {
+  var rd = fs.createReadStream(from);
+  var wr = fs.createWriteStream(to);
+  return new Promise(function(resolve, reject) {
+    rd.on('error', reject);
+    wr.on('error', reject);
+    wr.on('finish', resolve);
+    rd.pipe(wr);
+  }).catch(function(error) {
+    rd.destroy();
+    wr.end();
+    throw error;
+  });
+}
+