Puppeteer: staging commit.

install.js

@@ -0,0 +1,32 @@
+var Downloader = require('./lib/Downloader');
+var revision = require('./package').puppeteer.chromium_revision;
+var fs = require('fs');
+var ProgressBar = require('progress');
+
+var executable = Downloader.executablePath(revision);
+if (fs.existsSync(executable))
+    return;
+
+Downloader.downloadChromium(revision, onProgress)
+    .catch(error => {
+        console.error('Download failed: ' + error.message);
+    });
+
+var progressBar = null;
+function onProgress(bytesTotal, delta) {
+    if (!progressBar) {
+        progressBar = new ProgressBar(`Downloading Chromium - ${toMegabytes(bytesTotal)} [:bar] :percent :etas `, {
+            complete: '=',
+            incomplete: ' ',
+            width: 20,
+            total: bytesTotal,
+        });
+    }
+    progressBar.tick(delta);
+}
+
+function toMegabytes(bytes) {
+    var mb = bytes / 1024 / 1024;
+    return (Math.round(mb * 10) / 10) + ' Mb';
+}
+