why there is not even a background instance when running?

[heavenkiller2018]

it's weird that the background instance is missing! and all of manifest.json is correct.

{
  "manifest_version": 2,
  "name": "[name]",
  "version": "0.0.1",
  "description": "[description]",
  "options_ui": {
    "page": "./options/index.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "./content/index.global.js"
      ]
    }
  ],
  "icons": {
    "16": "./assets/icon-512.png",
    "48": "./assets/icon-512.png",
    "128": "./assets/icon-512.png"
  },
  "permissions": [
    "tabs",
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "./assets/icon-512.png",
    "default_popup": "./popup/index.html"
  },
  "background": [
    "background.js"
  ],
  "content_security_policy": "script-src-elem 'self' http://localhost:3309; object-src 'self'"
}