title: Default popup matching URL
body: <p>I test an online-survey application. I have hundreds of textboxes in my application in which I have to enter some numbers for testing purposes. So I am creating a Chrome extension to fill the form. I did it and it works almost as I expected - except there is a small issue.</p>
  
  <p><b>manifest.json:</b></p>
  
  <pre><code>{
    "name": "FillForm",
    "version": "1.0",
    "manifest_version": 2,
    "description": "FillForm",
    "browser_action": {
      "default_icon": "icon.png",
      "default_popup": "popup.html"
    },
    "permissions": ["activeTab"]
  }
  </code></pre>
  
  <p>Whenever I click on the browserAction button - it opens the popup.html where there is a textbox. If I enter <code>1</code> there, it will enter <code>1</code> for all the textboxes in my application - this is what I wanted.</p>
  
  <p>Now I want to open the <code>popup.html</code> only for my application, i.e. matching URL <code>http://example.com</code>, because I do not want to enter any information in any other pages. </p>
  
  <p>How can i achieve this?</p>