Examine source code of Google background

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Google background",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(66, 133, 244)",
      "toolbar_text": "rgb(241, 224, 182)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(244, 180, 0)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(244, 180, 0)",
      "popup": "rgba(15, 157, 88, 0.66)",
      "popup_text": "rgb(0, 0, 0)",
      "button_background_active": "rgba(219, 68, 55, 0.5)",
      "icons_attention": "rgb(219, 68, 55)",
      "ntp_background": "rgb(241, 224, 182)",
      "ntp_text": "rgb(68, 65, 82)",
      "sidebar": "rgb(66, 133, 244)",
      "tab_loading": "rgb(244, 180, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{67b90c20-7298-4d0d-b01e-11a1de6920bd}"
    }
  }
}