pdfjs-dist/extensions/chrome/manifest.json

{
  "manifest_version": 2,
  "name": "PDF Viewer",
  "version": "PDFJSSCRIPT_VERSION",
  "description": "Uses HTML5 to display PDF files directly in Chrome.",
  "permissions": [
    "webRequest", "webRequestBlocking",
    "http://*/*.pdf",
    "https://*/*.pdf",
    "file:///*/*.pdf"
  ],
  "background": {
    "page": "pdfHandler.html"
  }
}