title: Chrome Extension only works on "developer.chrome.com"
body: <p>This is my first chrome extension so please forgive me for asking such a novice question. My extension currently only works on 'developer.chrome.com' (icon has color) but I would like it to work on amazon.com (icon is gray). From googling, I didn't see anyone else come up with the same problem so I'm guessing it must be a mistake on my end. Here is my manifest.json:</p>
  
  <pre><code>{
    "name": "Reviews Extension",
    "version": "1.0",
    "description": "Get additional reviews from third party retailers",
    "permissions": [
      "https://api.walmartlabs.com/",
      "https://www.amazon.com/",
      "activeTab",
      "declarativeContent",
      "storage"
    ],
    "content_scripts": [
      {
        "matches": [
          "&lt;all_urls&gt;"
        ],
        "js": ["content.js"]
      }
    ],
    "options_page": "options.html",
    "background": {
      "scripts": [
        "background.js"
      ],
      "persistent": false
    },
    "page_action": {
      "default_popup": "popup.html",
      "default_icon": {
        "16": "images/get_started16.png",
        "32": "images/get_started32.png",
        "48": "images/get_started48.png",
        "128": "images/get_started128.png"
      }
    },
    "icons": {
      "16": "images/get_started16.png",
      "32": "images/get_started32.png",
      "48": "images/get_started48.png",
      "128": "images/get_started128.png"
    },
    "manifest_version": 2
  }
  </code></pre>
  
  <p>UPDATE:
  When I fiddled with background.js on the <code>pageUrl: {hostEquals: 'developer.chrome.com'}</code>, I found when I delete the URL, it no longer works on developer.chrome.com. But when I changed it to <code>https://www.amazon.com/</code> in place of developer.chrome.com, it didn't work on amazon's main page either.</p>
  
  <pre><code>'use strict';
  
  chrome.runtime.onInstalled.addListener(function () {
    chrome.storage.sync.set({ color: '#3aa757' }, function () {
      console.log('The color is green.');
    });
    chrome.declarativeContent.onPageChanged.removeRules(undefined, function () {
      chrome.declarativeContent.onPageChanged.addRules([{
        conditions: [new chrome.declarativeContent.PageStateMatcher({
          pageUrl: { hostEquals: 'developer.chrome.com' },
        })],
        actions: [new chrome.declarativeContent.ShowPageAction()]
      }]);
    });
  });
  </code></pre>
  
  <p>UPDATE 2:
  Got it working by change the pageURL in background.js. It had to be formatted in a very specific way: <code>www.amazon.com</code>, NOT <code>https://www.amazon.com</code>, <code>amazon.com</code>, or any other variations. I am still unable to add multiple websites by adding commas in between, any ideas there?</p>