Settings Overrides

Settings overrides are a way for extensions to override selected Chrome settings. The API is available only on Windows.

Homepage, Search Provider, and Startup Pages

Here is an example how homepage, search provider and startup pages can be modified in the extension manifest. Web sites used in the settings API must be verified (via Webmaster Tools) as being associated with that item in the Chrome Web Store. Note that if you verify ownership for a domain (for example, http://example.com) you can use any subdomain or page (for example, http://app.example.com or http://example.com/page.html) within your extension.

{
  "name": "My extension",
  ...
  "chrome_settings_overrides": {
    "homepage": "http://www.homepage.com",
    "search_provider": {
        "name": "name.__MSG_url_domain__",
        "keyword": "keyword.__MSG_url_domain__",
        "search_url": "http://www.foo.__MSG_url_domain__/s?q={searchTerms}",
        "favicon_url": "http://www.foo.__MSG_url_domain__/favicon.ico",
        "suggest_url": "http://www.foo.__MSG_url_domain__/suggest?q={searchTerms}",
        "instant_url": "http://www.foo.__MSG_url_domain__/instant?q={searchTerms}",
        "image_url": "http://www.foo.__MSG_url_domain__/image?q={searchTerms}",
        "search_url_post_params": "search_lang=__MSG_url_domain__",
        "suggest_url_post_params": "suggest_lang=__MSG_url_domain__",
        "instant_url_post_params": "instant_lang=__MSG_url_domain__",
        "image_url_post_params": "image_lang=__MSG_url_domain__",
        "alternate_urls": [
          "http://www.moo.__MSG_url_domain__/s?q={searchTerms}",
          "http://www.noo.__MSG_url_domain__/s?q={searchTerms}"
        ],
        "encoding": "UTF-8",
        "is_default": true
    },
    "startup_pages": ["http://www.startup.com"]
   },
   "default_locale": "de",
   ...
}

Customizing values

Values in the manifest can be customized in the following ways:

  • All values of the search_provider, homepage and startup_pages properties can be localized using the chrome.i18n API.
  • For external extensions, the search_provider, homepage and startup_pages URL values can be parametrized using a registry key. A new registry entry should be created next to the "update_url" key (see instructions here). The value name is "install_parameter", the value data is an arbitrary string:
    {
        "update_url": "https://clients2.google.com/service/update2/crx",
        "install_parameter": "Value"
      }
    All occurrences of the substring "__PARAM__" in the manifest URLs will be substituted with the "install_parameter" value. If “install_parameter” is absent, occurrences of "__PARAM__" are removed. Note that "__PARAM__" cannot be part of the hostname. It needs to occur after the first '/' in the URL.

Reference

An extension can override one or more of the following properties in the manifest:

  • homepage (string) - optional

    New value for the homepage.

  • search_provider (object) - optional

    A search engine

    Type Attribute Description
    string (optional) name

    Name of the search engine displayed to user. This may only be ommitted if prepopulated_id is set.

    string (optional) keyword

    Omnibox keyword for the search engine. This may only be ommitted if prepopulated_id is set.

    string (optional) favicon_url

    An icon URL for the search engine. This may only be ommitted if prepopulated_id is set.

    string search_url

    An search URL used by the search engine.

    string (optional) encoding

    Encoding of the search term. This may only be ommitted if prepopulated_id is set.

    string (optional) suggest_url

    If omitted, this engine does not support suggestions.

    string (optional) instant_url

    If omitted, this engine does not support instant.

    string (optional) image_url

    If omitted, this engine does not support image search.

    string (optional) search_url_post_params

    The string of post parameters to search_url

    string (optional) suggest_url_post_params

    The string of post parameters to suggest_url

    string (optional) instant_url_post_params

    The string of post parameters to instant_url

    string (optional) image_url_post_params

    The string of post parameters to image_url

    array of string (optional) alternate_urls

    A list of URL patterns that can be used, in addition to |search_url|.

    integer (optional) prepopulated_id

    Since Chrome 36.

    An ID of the built-in search engine in Chrome.

    boolean is_default

    Specifies if the search provider should be default.

  • startup_pages (array of string) - optional

    An array of length one containing a URL to be used as the startup page.