In Google Chrome, when you hover over a link, a small bar pops up on the bottom-left of the screen that tells you where the link takes you. I've installed a theme, and I like the theme, but I want to change the font color for this bottom bar:

I've done some investigative work, and found that some properties for themes are found inside of a manifest.json file. I've changed all these colors to black, but I don't see any difference. Am I editing the right file? Or has Chrome cached the file and won't reload it?
How else would I go about changing it?