title: how to execute content_script without clicking on the plugin icon in chrome plugin?
body: <p>I want to execute my content_script without clicking on the plugin icon.</p>
  <p>manifest.json</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>{
    "short_name": "my plugin",
    "name": "vanilla Chrome Extension",
  
    "manifest_version": 2,
    "permissions": ["activeTab", "tabs", "&lt;all_urls&gt;", "webNavigation"],
    "version": "0.0.1",
    "browser_action": {
      "default_popup": "popup.html",
      "default_title": "my plugin"
    },
    "content_scripts": [
      {
        "matches": ["&lt;all_urls&gt;"],
        "css": ["content-script.css"],
        " js ": ["content-script.js"],
        "run_at": "document_end"
      }
    ]
  }</code></pre>
  </div>
  </div>
  </p>
  <p>I also try document_idel and document_start</p>
  <p>content-script.js</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>console.log("inside plugin script");
  document.querySelectorAll("h1").style.backgroundColor = "#c1c1c1";</code></pre>
  </div>
  </div>
  </p>
  <p>I try to find out from docs but can't figure out what to do</p>