title: Can't inject content script into all IFRAMEs from my Chrome Extension
body: <p>In my Google Chrome Extension I need to be able to inject my <em>content script</em> into all <code>IFRAME</code>s on the page. To do this my original <code>manifest.json</code> was declared as such:</p>
  
  <pre><code>"content_scripts": [
      {
          "run_at": "document_end",
          "all_frames" : true,
          "matches": ["http://*/*", "https://*/*"],
          "js": ["content.js"]
      }
  ],
  </code></pre>
  
  <p>This seemed to have worked for most sites, until I came across an <code>IFRAME</code> that was declared as such:</p>
  
  <p>(From Chrome debugger)
  <img src="https://i.stack.imgur.com/DI5OU.png" alt="enter image description here"></p>
  
  <p>and here's the HTML for it:</p>
  
  <pre><code>&lt;iframe id="wysiwygtext_ifr" src='javascript:""' frameborder="0" allowtransparency="true" title="Rich Text Area." style="width: 100%; height: 341px; display: block;"&gt;&lt;/iframe&gt;
  </code></pre>
  
  <p>In this case my content script is not injected into that <code>IFRAME</code>.</p>
  
  <p>I tried changing the <code>matches</code> filter to <code>"matches": ["&lt;all_urls&gt;"]</code> but that still didn't do it.</p>
  
  <p>Is there any way for me to inject my <em>content script</em> in an <code>IFRAME</code> like that?</p>