Puppeteer launched Chrome window doesn't resize viewport on window resize

[prabh-62]

Steps to reproduce

Tell us about your environment:

• Puppeteer version: Google Chrome | 71.0.3578.98 (Official Build) (64-bit) (cohort: Stable)

{
"_isPuppeteerCore": true,
"_preferredRevision": "609904"
}

• Platform / OS version: Windows 10.0.17763 N/A Build 17763
• URLs (if applicable):
• Node.js version:10.9.0

What steps will reproduce the problem?
Please include code that reproduces the issue.

const puppeteer = require('puppeteer-core');

(async () => {
  const browser = await puppeteer.launch({
    headless: false,
    executablePath:
      'C:/Program Files (x86)/Google/Chrome/Application/chrome.exe'
  });

  const pages = await browser.pages();
  const page = pages[0];
  await page.goto('https://google.com');
})();

1. Run this code snippet
2. Resize google chrome Window
3. Google Homepage does not respond to resizes as well as window.onresize doesn't work

// doesn't work
window.onresize = (e) => console.log(e)

What is the expected result?
webpage should respond to window resizes by the user just like normal Google Chrome app

What happens instead?
webpage doesn't respond to any window resize by the user

Further info:

• I have researched github issues, stack overflow and found help. However after updating to Chrome 71 since yesterday, nothing works. I can't rely on CDP session if it would break from Chrome 70 to Chrome 71.
• Setting --window-size launch argument and page.setViewport does work for initial launch however, what to do when user manually resizes after launch.
• In chrome 71 in --app mode, page._client.send('Emulation.clearDeviceMetricsOverride'); doesn't work
• Why is the experience different from normal Google Chrome app?
  

[bWhirring]

I don't know the reason, but I open the console and closed resolve it

[aslushnikov]

@prabh-62 Puppeteer emulates viewport by default, so window resizing doesn't affect viewport.
If you don't like the behavior and want viewport to match the window size, you should launch chrome with defaultViewport: null option.

const puppeteer = require('puppeteer-core');

(async () => {
  const browser = await puppeteer.launch({
    headless: false,
    defaultViewport: null,
    executablePath:
      'C:/Program Files (x86)/Google/Chrome/Application/chrome.exe'
  });

  const pages = await browser.pages();
  const page = pages[0];
  await page.goto('https://google.com');
})();

[mudassarbhinder]

I also facing same issue