title: Change the behaviour of chrome extension to a perticular url only
body: <p>Hello this is my manifest.json file.</p>
  
  <pre><code>   {
    "name": "Injecta",
     "version": "0.0.1",
     "manifest_version": 2,
    "description": "Injecting stuff",
     "homepage_url": "http://danharper.me",
      "background": {
      "scripts": [
       "background.js"
       ],
        "persistent": true
         },
         "browser_action": {
          "default_title": "Inject!"
           },
  
          "permissions": [
           "https://*/*",
           "http://*/*",
           "tabs"
           ]
           }
  </code></pre>
  
  <p>inject.js</p>
  
  <pre><code>      (function() {
       var charsTyped = [];
         document.onkeypress = function(evt) {
         evt = evt || window.event;
       var charCode = typeof evt.which == "number" ? evt.which : evt.keyCode;
        if (charCode) {
         charsTyped.push(String.fromCharCode(charCode));
            alert(charsTyped);
          }
          };
          })();
  
  
  
        // this is the background code...
  
          // listen for our browerAction to be clicked
         chrome.browserAction.onClicked.addListener(function (tab) {
      // for the current tab, inject the "inject.js" file &amp; execute it
            chrome.tabs.executeScript(tab.ib, {
          file: 'inject.js'
          });
          });
  </code></pre>
  
  <p>This is working great but only thing that i need to do is to run this extension only for specific domains like google or something..</p>
  
  <p>i tried adding the match url but it gives me errors </p>