Access extensions in the chrome://extensions page [duplicate]

Answer 1

You can do it on your PC by enabling chrome://flags/#extensions-on-chrome-urls and adding the necessary url, chrome://extensions/, into "matches" in manifest.json but such extension won't be possible to install on a normal browser due to an invalid scheme error.

To avoid the fatal error, don't use manifest.json to inject the content script/style, do it manually in the background or popup script via chrome.tabs.insertCSS or chrome.tabs.executeScript:

• chrome://flags: enable Extensions on chrome:// URLs flag

• manifest.json:

  "permissions": ["chrome://*/*", "tabs"],
  "background": {
      "scripts": ["background.js"]
  },
  

• background.js:

  var chromeURLstylable;
  chrome.permissions.contains({origins: ["chrome://*/*"], permissions: ["tabs"]}, function(state) {
      chromeURLstylable = state;
      console.log("chrome:// urls support", state);
  
      if (chromeURLstylable) {
          chrome.tabs.onUpdated.addListener(function(tabId, info, tab) {
              if (info.status == "loading" && tab.url.indexOf("chrome://") == 0) {
                  chrome.tabs.insertCSS({
                      file: "style.css", 
                      runAt: "document_start",
                      allFrames: true
                  });
              }
          });
      }
  });
  

Beware of possible problems submitting such extension to the Chrome Webstore.