title: chrome.webNavigation.onCompleted - Event firing multiple times
body: <p>I load plagin for Inject code to page, the manifest code:</p>
  
  <pre><code>{
    "name": "any",
    "version": "1.0",
    "permissions": [
      "webNavigation",
      "*://*/*" 
    ],
    "background": {
      "scripts": ["background.js"],
      "persistent": false
    },
    "manifest_version": 2
  }
  </code></pre>
  
  <p>And the background.js:</p>
  
  <pre><code>chrome.webNavigation.onCompleted.addListener(function(details) {
      chrome.tabs.executeScript(details.tabId, {
          code: 'console.log("A")'
      });
  });
  </code></pre>
  
  <p>The problem is the event firing a few times after page load, I want the event just one time. What is my mistake?
  I would appreciate any help on.</p>