Examine source code of Rainbow Colors Animation

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Rainbow Colors Animation",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(255, 255, 255, 0.16)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(121, 121, 121)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgba(0, 0, 0, 0.06)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(121, 121, 121)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_hover": "rgba(225, 225, 225, 0.83)",
      "ntp_background": "rgb(183, 183, 183)",
      "popup_border": "rgb(0, 0, 0)",
      "sidebar_border": "rgb(128, 128, 128)",
      "sidebar_highlight": "rgb(225, 225, 225)",
      "sidebar": "rgb(183, 183, 183)",
      "tab_selected": "rgba(255, 255, 255, 0.37)",
      "toolbar_bottom_separator": "rgb(128, 128, 128)",
      "toolbar_field_border": "rgba(255, 255, 255, 0.34)",
      "toolbar_field_focus": "rgb(183, 183, 183)",
      "toolbar_top_separator": "rgba(255, 255, 255, 0)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9ec3c966-3e06-47db-8344-929b24a896c8}"
    }
  }
}