Thank you TheRealDannyyy
I tested your capx with r249 and NW.js 0.26.
The result is exactly same as I've posted.
If the window isn't resizable, it gives me a way off resolution.
If it's resizable, the resolution is close enough.
Then I turned on your workaround and the result is
An interesting thing to me is that "browser resolution" is off from "NW.js resolution", which gives correct numbers.
I've checked with the dev kit with my test and that is giving Browser resolution and that is what actually shown on screen I believe.
For now, we can use the workarounds.
Let's hope Chromium Dev fix this the bug.
And again, thank you for all of this.
I'm more an "artist" type. No idea what github and Chrominum are to be honest.
So it was hard for me to do all this stuff and I felt nobody look into the bug even after my report.
I'm really glad I found this thread and hope those info are helpful people who encounter the same issue.