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{
...
  "content_security_policy": "script-src 'self'; object-src 'self'; frame-src https://www.example.com; child-src https://www.example.com",
  "background": {
    "scripts": [
      "js/jquery/jquery.min.js",
      "src/bg/background.min.js"
    ],
    "persistent": true
  },
...
  "content_scripts": [
    {
      ...
      "css": [
        ...
        "src/inject/inject.min.css"
      ],
      "js": [
        ...
        "src/inject/inject.min.js"
      ]
    }
  ],
  "externally_connectable": {
    "matches": [
      "*://localhost/*",
      "*://*.example.com/*
    ]
  },
  "web_accessible_resources": [
    "src/inject/inject.html",
    "src/inject/infobar.html",
    "src/inject/infobar.min.js",
    "src/inject/frame.html"
  ],
  "sandbox": {
    "pages": [
      "src/inject/infobar.html",
      "src/inject/frame.html"
    ]
  }
}

var iframe = document.createElement("iframe");
iframe.scrolling = "no";
iframe.style.cssText = "display:none;";
...
$(iframe).load(function () {
    var message = {
        command: "render-frame",
        context: data,
        frameUrl: chrome.runtime.getURL("src/inject/frame.html")
    };
    iframe.contentWindow.postMessage(message, '*');
    iframe.style.cssText = "border: 0px; overflow: visible; padding: 0px; right: auto; width: 100%; height: " + toolbarHeight + "px; top: 0px; left: 0px; z-index: 2147483647; box-shadow: rgba(0, 0, 0, 0.498039) 0px 3px 10px; position: fixed; display: none;";
});
...
iframe.src = chrome.runtime.getURL("src/inject/infobar.html");
...
document.documentElement.appendChild(iframe);

window.addEventListener("message", function (event) {
    var command = event.data.command;
    switch (command) {
        case "render-frame":
            var frame = document.createElement("iframe");
            frame.scrolling = "no";
            frame.src = event.data.frameUrl;
            document.getElementById("content").appendChild(frame);
...
            break;
    }
});

<html>
<head>
    <style>
        html, body, iframe, h2 {
            margin: 0;
            border: 0;
            padding: 0;
            display: block;
            width: 100vw;
            height: 100vh;
            background: white;
            color: black;
        }
    </style>
</head>
<body>
<iframe src="https://www.example.com/page.html"></iframe>
</body>
</html>