docs(examples): render custom HTML to PDF

[guumaster]

add example to create an HTML page in memory, render it with puppeteer and save it as a pdf file.

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[guumaster]

I signed it!

[googlebot]

CLAs look good, thanks!

[JoelEinbinder]

Can you elaborate on a scenario where this would be useful for someone?

[guumaster]

Can you elaborate on a scenario where this would be useful for someone?

If you have a server that renders HTML and you want to generate pdf from any page, you can use this code to do it instead of navigating to an internal page with goto().

I've tried with setContent()/content() but even if you use await page.content() it wont show immediately. So after a while of going through the issues and docs I got this example working.

I thought it would be useful for somebody else.

Thanks for reviewing it!

[aslushnikov]

@guumaster The "goto hack" is a consequence of #728; I'd rather have it fixed than spreading the hack further.

#728 requires contributing upstream to Chromium and DevTools protocol; let me know if you want to give it a shot.

[guumaster]

Probably I can't contribute to #728 to Chromium.

This example may not be too important. But is not such a hack either, it is something that you can normally do with a browser, and puppeteer is meant to control a browser, isn't it? Maybe someone that needs this can find the code in this issue useful.

Thanks for your time anyway.

PS: You think you can merge it if I get the example working with setContent()/content() ?