Examine source code of Spelling Checker

{
  "manifest_version": 2,
  "name": "Spelling Checker",
  "short_name": "Spelling Checker",
  "description": "__MSG_appDesc__",
  "version": "1.0.0",
  "default_locale": "en",
  "author": "programmer",
  "applications": {
    "gecko": {
      "strict_min_version": "60.0",
      "id": "programmer2@gmail.com"
    }
  },
  "icons": {
    "16": "assets/images/icons/icon16.png",
    "32": "assets/images/icons/icon32.png",
    "48": "assets/images/icons/icon48.png",
    "64": "assets/images/icons/icon64.png",
    "128": "assets/images/icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "common/browser-polyfill.min.js",
      "config/config.js",
      "common/browserDetector.js",
      "core/utils.js",
      "common/utils.js",
      "common/eventBus.js",
      "common/messages.js",
      "common/i18nManager.js",
      "common/extensioni18nManager.js",
      "common/languageManager.js",
      "common/storageController.js",
      "common/extensionStorageController.js",
      "common/environmentAdapter.js",
      "common/extensionEnvironmentAdapter.js",
      "common/thunderbird.js",
      "common/extension-init.js",
      "common/tracker.js",
      "core/GraphemeSplitter.js",
      "core/Checker.js",
      "background/dictionarySync.js",
      "background/synonyms.js",
      "background/extension-main.js"
    ]
  },
  "content_scripts": [
    {
      "all_frames": true,
      "match_about_blank": true,
      "js": [
        "common/browser-polyfill.min.js",
        "common/sbd.js",
        "common/textStatistics.js",
        "common/calculateTextScore.js",
        "common/smoothscroll.js",
        "config/config.js",
        "core/ErrorProcessor.js",
        "core/utils.js",
        "common/utils.js",
        "common/browserDetector.js",
        "common/textToSpeech.js",
        "common/eventBus.js",
        "common/messages.js",
        "common/stringMap.js",
        "common/mutationObserversHub.js",
        "common/filteringMutationObserver.js",
        "common/domMeasurement.js",
        "common/i18nManager.js",
        "common/extensioni18nManager.js",
        "common/languageManager.js",
        "common/storageController.js",
        "common/extensionStorageController.js",
        "common/environmentAdapter.js",
        "common/extensionEnvironmentAdapter.js",
        "common/extension-init.js",
        "common/localStorageWrapper.js",
        "common/tracker.js",
        "common/gdocs/googleDocs.js",
        "content/gdocs/adapters/canvas.js",
        "content/gdocs/adapters/html.js",
        "common/googleSlides.js",
        "common/latexParser.js",
        "common/overleaf.js",
        "common/notion.js",
        "common/thunderbird.js",
        "common/dictionary.js",
        "common/tweaksManager.js",
        "common/tweaksManagerRules.js",
        "components/premiumTeaser/premiumTeaser.js",
        "components/ratingTeaser/ratingTeaser.js",
        "components/select/select.js",
        "components/icon/icon.js",
        "components/menu/menu.js",
        "components/score/score.js",
        "components/toggle/toggle.js",
        "components/hint/hint.js",
        "components/messagePopup/messagePopup.js",
        "components/packageBadge/packageBadge.js",
        "content/debounce.js",
        "content/domWalker.js",
        "content/checkStatus.js",
        "content/ceElementInspector.js",
        "content/mirror.js",
        "content/formElementMirror.js",
        "content/inputAreaWrapper.js",
        "content/formElementWrapper.js",
        "content/ceElementWrapper.js",
        "content/gdocs/svgElementWrapper.js",
        "content/overleafSourceEditorWrapper.js",
        "content/overleafRichEditorWrapper.js",
        "content/highlighter.js",
        "content/toolbar.js",
        "content/dialog.js",
        "content/errorCard.js",
        "content/synonymsCard.js",
        "content/ltAssistant.js",
        "content/extension-main.js",
        "welcome/welcome.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*",
        "file:///*"
      ],
      "run_at": "document_idle"
    },
    {
      "all_frames": true,
      "js": [
        "/js/1.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "match_about_blank": true,
      "run_at": "document_start"
    },
    {
      "all_frames": true,
      "match_about_blank": true,
      "css": [
        "common/fonts.css",
        "content/styles/styles.css"
      ],
      "matches": [
        "http://*/*",
        "https://*/*",
        "file:///*"
      ],
      "run_at": "document_idle"
    },
    {
      "all_frames": true,
      "js": [
        "content/gdocs/injector.js"
      ],
      "matches": [
        "*://docs.google.com/document/*"
      ],
      "run_at": "document_start"
    },
    {
      "all_frames": true,
      "js": [
        "content/languagetool/injector.js"
      ],
      "matches": [
        "*://languagetool.org/*"
      ],
      "run_at": "document_start"
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "chrome_style": false,
    "open_in_tab": true
  },
  "browser_action": {
    "default_icon": "assets/images/icons/icon16.png",
    "default_title": "LanguageTool",
    "default_popup": "popup/popup.html"
  },
  "web_accessible_resources": [
    "assets/fonts/*.woff2",
    "assets/styles/*",
    "common/*.css",
    "common/*.js",
    "content/*.css",
    "content/*.js",
    "config/*.js",
    "welcome/*.js",
    "welcome/welcome.css",
    "welcome/managedLoginRedirectUri.html",
    "welcome/loginRedirectUri.html",
    "welcome/templates/index.html",
    "content/iframes/rating/*.html",
    "content/iframes/premiumErrors/*.html",
    "content/iframes/historicPremiumErrors/*.html",
    "assets/images/*"
  ]
}