Examine source code of Quick Copy Plus

{
  "name": "Quick Copy - most powerful clipboard manager",
  "description": "A superpowered clipboard inside your browser.",
  "version": "2.4.2",
  "manifest_version": 2,
  "icons": {
    "16": "icon_16.png",
    "32": "icon_32.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "permissions": [
    "storage",
    "clipboardRead",
    "http://*/*",
    "https://*/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content_scripts/main.js"
      ]
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_title": "Quick Copy",
    "default_popup": "browser_action/index.html"
  },
  "background": {
    "scripts": [
      "background/main.js"
    ],
    "persistent": false
  },
  "commands": {
    "copy-1": {
      "suggested_key": {
        "default": "Alt+Shift+1"
      },
      "description": "Copy text into slot 1"
    },
    "copy-2": {
      "suggested_key": {
        "default": "Alt+Shift+2"
      },
      "description": "Copy text into slot 2"
    },
    "copy-3": {
      "description": "Copy text into slot 3"
    },
    "copy-4": {
      "description": "Copy text into slot 4"
    },
    "copy-5": {
      "description": "Copy text into slot 5"
    },
    "copy-6": {
      "description": "Copy text into slot 6"
    },
    "copy-7": {
      "description": "Copy text into slot 7"
    },
    "copy-8": {
      "description": "Copy text into slot 8"
    },
    "copy-9": {
      "description": "Copy text into slot 9"
    },
    "paste-1": {
      "suggested_key": {
        "default": "Ctrl+Shift+1"
      },
      "description": "Paste text from slot 1"
    },
    "paste-2": {
      "suggested_key": {
        "default": "Ctrl+Shift+2"
      },
      "description": "Paste text from slot 2"
    },
    "paste-3": {
      "description": "Paste text from slot 3"
    },
    "paste-4": {
      "description": "Paste text from slot 4"
    },
    "paste-5": {
      "description": "Paste text from slot 5"
    },
    "paste-6": {
      "description": "Paste text from slot 6"
    },
    "paste-7": {
      "description": "Paste text from slot 7"
    },
    "paste-8": {
      "description": "Paste text from slot 8"
    },
    "paste-9": {
      "description": "Paste text from slot 9"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c9f7e23e-2f0a-40da-91bb-b38601110ca2}"
    }
  }
}