chore: add utils/bisect.js to bisect chromium revisions (#3511)

This patch adds a new utility - `utils/bisect.js` - that accepts
a range of Chromium revisions and a pptr script and bisects the
range to figure when the script breaks.

The Puppeteer Script, given to the tool, should be exiting
with non-zero code to signify malfunctioning.

Example:
```
$ node utils/bisect.js --good 577361 --bad 599821 a.js
```

utils/bisect.js

@@ -0,0 +1,194 @@
+#!/usr/bin/env node
+/**
+ * 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 URL = require('url');
+const debug = require('debug');
+const pptr = require('..');
+const browserFetcher = pptr.createBrowserFetcher();
+const path = require('path');
+const fs = require('fs');
+const {fork} = require('child_process');
+
+const COLOR_RESET = '\x1b[0m';
+const COLOR_RED = '\x1b[31m';
+const COLOR_GREEN = '\x1b[32m';
+const COLOR_YELLOW = '\x1b[33m';
+
+const argv = require('minimist')(process.argv.slice(2), {});
+
+const help = `
+Usage:
+  node bisect.js --good <revision> --bad <revision> <script>
+
+Parameters:
+  --good    revision that is known to be GOOD
+  --bad     revision that is known to be BAD
+  <script>  path to the script that returns non-zero code for BAD revisions and 0 for good
+
+Example:
+  node utils/bisect.js --good 577361 --bad 599821 simple.js
+`;
+
+if (argv.h || argv.help) {
+  console.log(help);
+  process.exit(0);
+}
+
+if (typeof argv.good !== 'number') {
+  console.log(COLOR_RED + 'ERROR: expected --good argument to be a number' + COLOR_RESET);
+  console.log(help);
+  process.exit(1);
+}
+
+if (typeof argv.bad !== 'number') {
+  console.log(COLOR_RED + 'ERROR: expected --bad argument to be a number' + COLOR_RESET);
+  console.log(help);
+  process.exit(1);
+}
+
+const scriptPath = path.resolve(argv._[0]);
+if (!fs.existsSync(scriptPath)) {
+  console.log(COLOR_RED + 'ERROR: Expected to be given a path to a script to run' + COLOR_RESET);
+  console.log(help);
+  process.exit(1);
+}
+
+(async(scriptPath, good, bad) => {
+  const span = Math.abs(good - bad);
+  console.log(`Bisecting ${COLOR_YELLOW}${span}${COLOR_RESET} revisions in ${COLOR_YELLOW}~${span.toString(2).length}${COLOR_RESET} iterations`);
+
+  while (true) {
+    const middle = Math.round((good + bad) / 2);
+    const revision = await findDownloadableRevision(middle, good, bad);
+    if (!revision || revision === good || revision === bad)
+      break;
+    let info = browserFetcher.revisionInfo(revision);
+    const shouldRemove = !info.local;
+    info = await downloadRevision(revision);
+    const exitCode = await runScript(scriptPath, info);
+    if (shouldRemove)
+      await browserFetcher.remove(revision);
+    let outcome;
+    if (exitCode) {
+      bad = revision;
+      outcome = COLOR_RED + 'BAD' + COLOR_RESET;
+    } else {
+      good = revision;
+      outcome = COLOR_GREEN + 'GOOD' + COLOR_RESET;
+    }
+    const span = Math.abs(good - bad);
+    console.log(`- ${COLOR_YELLOW}r${revision}${COLOR_RESET} was ${outcome}. Bisecting [${good}, ${bad}] - ${COLOR_YELLOW}${span}${COLOR_RESET} revisions and ${COLOR_YELLOW}~${span.toString(2).length}${COLOR_RESET} iterations`);
+  }
+
+  const [goodSha, badSha] = await Promise.all([
+    revisionToSha(good),
+    revisionToSha(bad),
+  ]);
+  console.log(`RANGE: https://chromium.googlesource.com/chromium/src/+log/${goodSha}..${badSha}`);
+})(scriptPath, argv.good, argv.bad);
+
+function runScript(scriptPath, revisionInfo) {
+  const log = debug('bisect:runscript');
+  log('Running script');
+  const child = fork(scriptPath, [], {
+    stdio: ['inherit', 'inherit', 'inherit', 'ipc'],
+    env: {
+      PUPPETEER_EXECUTABLE_PATH: revisionInfo.executablePath,
+    },
+  });
+  return new Promise((resolve, reject) => {
+    child.on('error', err => reject(err));
+    child.on('exit', code => resolve(code));
+  });
+}
+
+async function downloadRevision(revision) {
+  const log = debug('bisect:download');
+  log(`Downloading ${revision}`);
+  let progressBar = null;
+  let lastDownloadedBytes = 0;
+  return await browserFetcher.download(revision, (downloadedBytes, totalBytes) => {
+    if (!progressBar) {
+      const ProgressBar = require('progress');
+      progressBar = new ProgressBar(`- downloading Chromium r${revision} - ${toMegabytes(totalBytes)} [:bar] :percent :etas `, {
+        complete: '=',
+        incomplete: ' ',
+        width: 20,
+        total: totalBytes,
+      });
+    }
+    const delta = downloadedBytes - lastDownloadedBytes;
+    lastDownloadedBytes = downloadedBytes;
+    progressBar.tick(delta);
+  });
+  function toMegabytes(bytes) {
+    const mb = bytes / 1024 / 1024;
+    return `${Math.round(mb * 10) / 10} Mb`;
+  }
+}
+
+async function findDownloadableRevision(rev, from, to) {
+  const log = debug('bisect:findrev');
+  const min = Math.min(from, to);
+  const max = Math.max(from, to);
+  log(`Looking around ${rev} from [${min}, ${max}]`);
+  if (await browserFetcher.canDownload(rev))
+    return rev;
+  let down = rev;
+  let up = rev;
+  while (min <= down || up <= max) {
+    const [downOk, upOk] = await Promise.all([
+      down > min ? probe(--down) : Promise.resolve(false),
+      up < max ? probe(++up) : Promise.resolve(false),
+    ]);
+    if (downOk)
+      return down;
+    if (upOk)
+      return up;
+  }
+  return null;
+
+  async function probe(rev) {
+    const result = await browserFetcher.canDownload(rev);
+    log(`  ${rev} - ${result ? 'OK' : 'missing'}`);
+    return result;
+  }
+}
+
+async function revisionToSha(revision) {
+  const json = await fetchJSON('https://cr-rev.appspot.com/_ah/api/crrev/v1/redirect/' + revision);
+  return json.git_sha;
+}
+
+function fetchJSON(url) {
+  return new Promise((resolve, reject) => {
+    const agent = url.startsWith('https://') ? require('https') : require('http');
+    const options = URL.parse(url);
+    options.method = 'GET';
+    options.headers = {
+      'Content-Type': 'application/json'
+    };
+    const req = agent.request(options, function(res) {
+      let result = '';
+      res.setEncoding('utf8');
+      res.on('data', chunk => result += chunk);
+      res.on('end', () => resolve(JSON.parse(result)));
+    });
+    req.on('error', err => reject(err));
+    req.end();
+  });
+}