White screen splashes when using dark mode

[megastallman]

Hi guys! That is basically a Chromium issue, that was half-fixed and broken again by its devs.
I'm using "chrome://flags/ -> Force Dark Mode for Web Contents -> Selective Inversion of Everything" setting, but earlier - was using the Dark Reader plugin instead. The problem is the same, when I open a new page - I see the white canvas only. It can last up to 20 seconds if the site is really heavy and the connection is too slow. Or doesn't happen at all if the site is precached already or is lightweight enough. So at some point white color is hardcoded to be used by default. And it doesn't respect the Dark Mode option.
Does anyone have an idea, at least which component is that? I'm comfortable with UC rebuild process, so I can experiment with its code.

P.S. - Thanks again for the best browser in the universe.

[kramred]

You could first test one of the dark mode new tab extensions, like this one: https://github.com/dandydanny/darknewtab – it uses the mechanism described here (Overriding Chrome pages)

Or, if that is not used for opening a link in a new window/tab (probably isn't) – try looking in one of these directories of the unpacked sources: chrome/browser/resources/ntp4 or chrome/browser/resources/new_tab_page for something that could be used as default empty page.

Although, the background for opening a link in an empty new window/tab might be defined somewhere else in chrome/browser or even other places… maybe in chrome/browser/ui/webui/new_tab_page/new_tab_page_ui.cc in NewTabPageUI::UpdateBackgroundColor (?)

[megastallman]

Thanks for your time Kramred, although looks like the white flash happens much earlier than this code gets run.
So, my build script pre-deletes the build/src/out/Default directory, to avoid any leftovers.
Darknewtab extension - just makes the tab dark only after that white flash. As for chrome/browser/resources/ntp4 and chrome/browser/resources/new_tab_page - I've replaced background-color: white with green, but still have never seen that color. Also - commented out(tried differet combinations) the UpdateBackgroundColor(theme); line in new_tab_page_ui.cc. But still - nothing changes. As it was before patch, I'm still getting:

1. White canvas - 1-10 seconds.
2. Dark canvas - less than a second(probably the Google's partial fix, that I haven't noticed last year).
3. Page contents get loaded.

[BachoSeven]

Relevant (old) patch, which I link because it contains references to (old) issues and threads on this (old) problem.
A newer issue can be found here.

[BachoSeven]

possibly relevant: https://chromium-review.googlesource.com/c/chromium/src/+/1418650

[kramred]

Okay, I think I found what controls this → Themes

The minimal way to change only the background color of new windows/tabs to rgb(0, 0, 0) would be creating a manifest.json file with the content below in an empty folder and loading it via chrome://extensions/ "Load unpacked"

{
  "manifest_version": 2,
  "version": "3",
  "name": "ntp_background_000",
  "theme": {
    "colors": {
      "ntp_background": [0, 0, 0]
    }
  }
}

See the article What are themes? and e.g. the source code of the Just Black Chrome Theme with the following manifest.json for a more fitting overall design idea:

{
"update_url": "https://clients2.google.com/service/update2/crx",

  "manifest_version": 2,
  "version": "3",
  "name": "Just Black",
  "description": "Midnight monochrome",

 "theme": {
    "colors": {
      "frame": [ 0,0,0],
      "toolbar": [45,45,45],
      "ntp_background": [0,0,0],


      "tab_text": [255,255,255],
      "bookmark_text": [255,255,255],
      "tab_background_text": [255,255,255],
      "tab_background_text_inactive": [ 255,255,255],
      "tab_background_text_incognito": [ 255,255,255 ],
      "tab_background_text_incognito_inactive": [ 255,255,255],


      "ntp_text": [125,134,142]

       },      

    "tints" : {
      "buttons": [ 0.2, 0.2, 0.9 ],
      "frame_incognito": [ -1, -1, -1 ],
      "frame_inactive": [ -1, -1, -1],
      "frame_incognito_inactive": [  -1, -1, -1]
    
     }
  }
}

You can revert the Theme in chrome://settings/appearance under "Theme"

The Chromium source file chrome/browser/themes/browser_theme_pack.cc specifies the "Strings used by themes to identify colors in the JSON."

[megastallman]

Probably something's fixed on version 95, portable Linux version.
Running UC as:

/somewhere/chrome --enable-features=OverlayScrollbar --force-dark-mode  %U

At least now, I can resize the UC window on youtube and other sites, wait for long DNS responces and static contents load, and finally there are no white splashes. The canvas begins drawing black, according to my KDE theme. Thanks everyone!