Examine source code of ViewPDF Browser

{
  "manifest_version": 2,
  "name": "No PDF Download",
  "description": "Opens all PDF files directly in the browser.",
  "version": "1.0.6",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "src/headers.js",
      "src/background.js"
    ]
  },
  "icons": {
    "128": "icon_128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{30d7ee59-96e4-4136-9d13-5f2af694dce9}"
    }
  }
}