Why are some Chrome extensions grayed out in the extension toolbar?

It's because Google changed something, i can testify on my own custom extension i wrote, it used to have a colorful icon and suddenly after Chrome updated itself the icon became gray (however the extension functioned properly).

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For the developers who troubleshoot this annoying bug, (and google through it to this question), i answered to a similar question in Stack Overflow.

I had to find out more so iv'e reverse engineered the famous AD Block extension (that has a non-gray icon).

I tried to change things in the extension's manifast.json file, Eventually i found out that the following setting keeps the icon colorfull:

{
  ...

  "browser_action": {
    "default_icon": "icons/icon-32.png"
  },

  ...
}

• source - https://stackoverflow.com/a/38604189/3191896