Avoid cross-origin iframe issues when loading PDF in print preview

chrome/browser/resources/pdf/manifest.json

 {
   // chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai
   "manifest_version": 2,
   "key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDN6hM0rsDYGbzQPQfOygqlRtQgKUXMfnSjhIBL7LnReAVBEd7ZmKtyN2qmSasMl4HZpMhVe2rPWVVwBDl6iyNE/Kok6E6v6V3vCLGsOpQAuuNVye/3QxzIldzG/jQAdWZiyXReRVapOhZtLjGfywCvlWq7Sl/e3sbc0vWybSDI2QIDAQAB",
   "name": "<NAME>",
   "version": "1",
   "description": "",
   "offline_enabled": true,
   "incognito": "split",
   "permissions": [
     "<all_urls>",
     "resourcesPrivate"
   ],
   "mime_types": [
     "application/pdf"
   ],
   "content_security_policy": "script-src 'self' blob: filesystem: chrome://resources; object-src * blob: filesystem: data:; plugin-types application/x-google-chrome-pdf",
-  // This is to work-around an issue where this extension is not granted
-  // permission to access chrome://resources when iframed for print preview.
-  // See https://crbug.com/444752.
-  "content_scripts": [
-    {
-      "matches": ["chrome://print/*"],
-      "js": ["content_script.js"]
-    }
-  ],
   "mime_types_handler": "index.html",
   "web_accessible_resources": [
-    "index.html"
+    "*.js",
+    "*.html",
+    "*.css",
+    "*.png"
   ]
 }