Error in launching Chrome Extension for a specific page

Solution 1:

You are adding a browser action popup, which adds a button to the top-right of your browser. (It's probably invisible because you haven't specified an image for it. There should be some empty space to the right of your address bar; try clicking it to see your Hello.html in a popup.)

What you want is a content script. Content scripts can get injected into every page that Chrome loads. You can use the matches and exclude_matches sub-items in your manifest file to specify which pages get your injected script.

{
  "name": "Hello",
  "version": "1.0",
  "description": "Says hello to Google",
  "permissions": ["tabs", "*://*.google.com/*"],
  "content_scripts": [
    {
      "matches": ["*://*.google.com/*"],
      "js": ["hello.js"]
    }
  ]
}

Make sure you rename Hello.html to hello.js (and get rid of the <script> tags).

Note also that I changed your http://*.google.com/ to *://*.google.com/* so that it will apply to Google over HTTP and HTTPS (and the trailing * ensures that it will apply to all pages on google.com, not just the main page).

Solution 2:

I came across this answer trying to find a way to only enable the icon on certain pages this is how I did it. Docs

background.js

chrome.runtime.onInstalled.addListener(function() {
  chrome.tabs.onActivated.addListener(async info => {
    const tab = await chrome.tabs.get(info.tabId);
    
    const isGithub = tab.url.startsWith('https://github.com/');
    isGithub 
      ? chrome.action.enable(tab.tabId) 
      : chrome.action.disable(tab.tabId);
  });
});

make sure to add tabs permission in manifest

Solution 3:

First of all there are 2 types of extensions:

1. Browser Action - which work for multiple websites or almost all websites
2. Page Action - which work for specific websites or webpages [which is needed 
   in our case]

Follow these steps to show your extension only on google:

Step 1: Go to manifest.json file and add the below code snippet

        "background":{
           "scripts":["background.js"],
           "persistent":false
         }
         
         ***also make sure you have page action not browser action** 
        
         "page_action" : { "default_popup":"your_popup.html" }

Step 2: Now add permissions in manifest:
        
        "permissions":["declarativeContent"]

Step 3: Now create background.js in root folder of extension and add the 
        below code in it, this will let the extension to work only on 
        urls that contain google.com
        
        // When the extension is installed or upgraded ...
        chrome.runtime.onInstalled.addListener(function() {
         // Replace all rules ...
         chrome.declarativeContent.onPageChanged.removeRules(undefined, 
      function() {
         // With a new rule ...
         chrome.declarativeContent.onPageChanged.addRules([
         {
          // That fires when a page's URL contains a 'g' ...
          conditions: [
          new chrome.declarativeContent.PageStateMatcher({
            pageUrl: { urlContains: 'google.com' },
          })
         ],
          // And shows the extension's page action.
          actions: [ new chrome.declarativeContent.ShowPageAction() ]
        }
      ]);
    });
  });

Step 4: Now reload your extension, you'll find that your extension will work 
        only for google.com

Hope this solved your query, If Yes, then Upvote the answer Thanks!