Add ability to remove default args via config

[walter]

When trying to use chromic_pdf in combination with pages that contain WebGL images, there are two default args in ChromeRunner that prevent it from working.

• --headless (rather than --headless=new)
• --disable-gpu which, despite its name, will disable software based webgl rendering in addition to hardware accelerated webgl

Based on my experimentation, simply overriding these in :chrome_args is not enough. Once they are declared, they can't be overridden by further switches.

Instead of just taking these out, and maybe break other people's projects, I think adding the ability to remove the args via configuration is a more useful feature.

[maltoe]

Hi @walter,

thanks for the contribution! 💜 Code looks good to me, though I'd prefer if we could extend chrome_args instead of adding a new option for this.

Please add yourself to the top of the changelog as well, something like

## Unreleased

### Added

- ... (@walter)

[maltoe]

Hi @walter

Had a few stylistic nitpicks still. If you don't want to continue working on this, I can also merge it in and refactor afterwards. As you prefer.

Thanks again!

[maltoe]

Let's be liberal in what the API can accept; a List.wrap/1 somewhere will allow you to accept strings or lists for either of the options, and then we don't need this note in the docs.

Suggested change

_Note: `:append` expects a string whereas `:remove` expects a list._

[maltoe]

# above
@type extended_chrome_args :: [{:append, binary() | [binary()]} | {:remove, binary() | [binary()]}]

Suggested change

	| {:chrome_args, binary() | map()}
	| {:chrome_args, binary() | extended_chrome_args()}

[maltoe]

I think the implementation could use another round of polishing :)

Suggested change

	|> append_chrome_args_if(opts[:chrome_args])
	|> handle_chrome_args(opts[:chrome_args])

Maybe go for a unified handler function. 3 Clauses, nil if option not set, then a is_binary clause for the original behaviour, and a new is_list clause for handling the extended args. Extracting options from this list should then be something like:

remove = List.wrap(Keyword.get(extended, :remove, []))

[walter]

Hi @walter

Had a few stylistic nitpicks still. If you don't want to continue working on this, I can also merge it in and refactor afterwards. As you prefer.

Thanks again!

Thanks for the feedback. Jibes with some thoughts I had myself, but was distracted by other work. I hadn't used List.wrap before, nice!

Have a look at latest and let me know if there is anything else.

[maltoe]

Thanks again!

[maltoe]

Released as v1.16.1