Examine source code of ScholarHub

{
  "manifest_version": 2,
  "name": "ScholarHub",
  "description": "It simplifies usage of google scholar and scihub",
  "version": "1.1",
  "web_accessible_resources": [
    "icons/scihub.png"
  ],
  "permissions": [
    "contextMenus",
    "*://sci-hub.now.sh/*",
    "storage",
    "tabs",
    "webNavigation"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.scholar.google.com/scholar?*"
      ],
      "js": [
        "scripts/content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/scihub.png"
  },
  "commands": {
    "scholarKey": {
      "suggested_key": {
        "default": "Alt+G"
      },
      "description": "It opens Google Scholar"
    },
    "scihubKey": {
      "suggested_key": {
        "default": "Ctrl+Space"
      },
      "description": "It opens Sci-Hub"
    }
  }
}