feat: Disabled the default browser check for Chromium (#1781)

[mariyan-borisov]

Essentially closes #1781.

I didn't want to touch DEFAULT_CHROME_FLAGS, as it only contains the default flags of chromium-launcher, so that's why I added EXTRA_CHROME_FLAGS. The new list can also be used to add more command line flags in the future, there's plenty to pick from: https://peter.sh/experiments/chromium-command-line-switches/.
The thing I'm not sure about is the correctness of my test.

[coveralls]

Coverage remained the same at 100.0% when pulling 4ec9c7d on mariyan-borisov:disable-chromium-default-browser-check into 7ee3c44 on mozilla:master.

[Rob--W]

I think that it's fine to add the flag to DEFAULT_CHROME_FLAGS, because there is no real need to distinguish between default flags from upstream, and what we consider to be default flags. We already filter out flags that we don't want anyway.

This flag could be a useful default for testing. Have you tried to get this flag in the upstream package?

[mariyan-borisov]

This flag could be a useful default for testing. Have you tried to get this flag in the upstream package?

No, I haven't. I'm not sure about the goal of that project and whether they are interested in adding this flag as a default.

[mariyan-borisov]

Okay, I created an issue in the project of chrome-launcher. Lets see what they think about my suggestion.

[rpl]

@mariyan-borisov thanks for fixing the issue on the upstream project!

I'm closing this in favor of updating the chrome-launcher dependency once released.