"Force Dark Mode for Web Contents" in Google Chrome/Chromium using command line switch(es)

I trying to enable dark mode for web content based on time of day.
However I can not enable it using command line switches.

Nothing of that works for me:

--dark --force-dark-mode --blink-settings=inversion_method=cielab_based,image_behavior=selective,text_lightness_threshold=150,background_lightness_threshold=205

Is there any possible way to enable it using command line switches?

Force Dark Mode for Web Contents flag

2 Answers

This was answered in Google Groups:
However looks like there is not way to specify exact flag value.

Lily Chen wrote:

Try --enable-features=WebContentsForceDark

The params for each of the modes are listed here: defined here:

You can specify the params for each group via command line using --force-fieldtrial-params:

And then you can force yourself into a particular group via command line using --force-fieldtrials:

You'll have to play around with the syntax (it's pretty tricky/annoying), but that should get you started.

There is actually a way to set whatever option of the flag you want to use. So, for "Force Dark Mode for Web Contents" it goes like this:

1. Enabled:

--enable-features=WebContentsForceDark

2. Enabled with simple HSL-based inversion:

 --enable-features=WebContentsForceDark:inversion_method/hsl_based/image_behavior/none/text_lightness_threshold/256/background_lightness_threshold/0

3. Enabled with simple CIELAB-based inversion:

 --enable-features=WebContentsForceDark:inversion_method/cielab_based/image_behavior/none/text_lightness_threshold/256/background_lightness_threshold/0

4. Enabled with simple RGB-based inversion:

--enable-features=WebContentsForceDark:inversion_method/rgb_based/image_behavior/none/text_lightness_threshold/256/background_lightness_threshold/0

5. Enabled with selective image inversion:

--enable-features=WebContentsForceDark:inversion_method/cielab_based/image_behavior/selective/text_lightness_threshold/256/background_lightness_threshold/0

6. Enabled with selective inversion of non-image elements:

 --enable-features=WebContentsForceDark:inversion_method/cielab_based/image_behavior/none/text_lightness_threshold/150/background_lightness_threshold/205

7. Enabled with selective inversion of everything:

 --enable-features=WebContentsForceDark:inversion_method/cielab_based/image_behavior/selective/text_lightness_threshold/150/background_lightness_threshold/205

8. Disabled:

 --disable-features=WebContentsForceDark

This was tested on Chrome Stable: Version 89.0.4389.114 (Official Build) (64-bit) and on Chromium: Version 92.0.4480.0 (Developer Build) (64-bit)

After setting a flag, you can check it out if it is used by going to chrome://version/, in the "Command Line" field.