Examine source code of kinDraw

{
  "name": "kinDraw",
  "manifest_version": 2,
  "description": "This adds canvas for drawing a picture and inserting them in kintone comment boxes.",
  "homepage_url": "https://github.com/miyajan/kinDraw",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_title": "kinDraw"
  },
  "permissions": [
    "https://*.cybozu.com/k/*",
    "https://*.cybozu-dev.com/k/*",
    "https://*.kintone.com/k/*",
    "https://*.kintone-dev.com/k/*",
    "https://*.cybozu.cn/k/*",
    "https://*.cybozu-dev.cn/k/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.cybozu.com/k/*",
        "https://*.cybozu-dev.com/k/*",
        "https://*.kintone.com/k/*",
        "https://*.kintone-dev.com/k/*",
        "https://*.cybozu.cn/k/*",
        "https://*.cybozu-dev.cn/k/*"
      ],
      "js": [
        "js/content.js"
      ],
      "css": [
        "css/content.css"
      ],
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "js/kinDraw.js"
  ],
  "version": "1.0.0"
}