A chrome extension can inject script into the page, this is called content script.

https://developer.chrome.com/extensions/getstarted
https://developer.chrome.com/extensions/content_scripts
https://developer.chrome.com/extensions/messaging

图标变灰的问题

Add browser_action.default_icon in your manifest.json file

“`
{
…

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

…
}
“`

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