chrome.types

Description: The chrome.types API contains type declarations for Chrome.
Availability: Since Chrome 24.

Chrome settings

The ChromeSetting prototype provides a common set of functions (get(), set(), and clear()) as well as an event publisher (onChange) for settings of the Chrome browser. The proxy settings examples demonstrate how these functions are intended to be used.

Scope and life cycle

Chrome distinguishes between three different scopes of browser settings:

regular
Settings set in the regular scope apply to regular browser windows and are inherited by incognito windows if they are not overwritten. These settings are stored to disk and remain in place until they are cleared by the governing extension, or the governing extension is disabled or uninstalled.
incognito_persistent
Settings set in the incognito_persistent scope apply only to incognito windows. For these, they override regular settings. These settings are stored to disk and remain in place until they are cleared by the governing extension, or the governing extension is disabled or uninstalled.
incognito_session_only
Settings set in the incognito_session_only scope apply only to incognito windows. For these, they override regular and incognito_persistent settings. These settings are not stored to disk and are cleared when the last incognito window is closed. They can only be set when at least one incognito window is open.

Precedence

Chrome manages settings on different layers. The following list describes the layers that may influence the effective settings, in increasing order of precedence.

  1. System settings provided by the operating system
  2. Command-line parameters
  3. Settings provided by extensions
  4. Policies

As the list implies, policies might overrule any changes that you specify with your extension. You can use the get() function to determine whether your extension is capable of providing a setting or whether this setting would be overridden.

As discussed above, Chrome allows using different settings for regular windows and incognito windows. The following example illustrates the behavior. Assume that no policy overrides the settings and that an extension can set settings for regular windows (R) and settings for incognito windows (I).

  • If only (R) is set, these settings are effective for both regular and incognito windows.
  • If only (I) is set, these settings are effective for only incognito windows. Regular windows use the settings determined by the lower layers (command-line options and system settings).
  • If both (R) and (I) are set, the respective settings are used for regular and incognito windows.

If two or more extensions want to set the same setting to different values, the extension installed most recently takes precedence over the other extensions. If the most recently installed extension sets only (I), the settings of regular windows can be defined by previously installed extensions.

The effective value of a setting is the one that results from considering the precedence rules. It is used by Chrome.

Summary

Types
ChromeSettingScope
LevelOfControl
ChromeSetting

Types

ChromeSettingScope

The scope of the ChromeSetting. One of
  • regular: setting for the regular profile (which is inherited by the incognito profile if not overridden elsewhere),
  • regular_only: setting for the regular profile only (not inherited by the incognito profile),
  • incognito_persistent: setting for the incognito profile that survives browser restarts (overrides regular preferences),
  • incognito_session_only: setting for the incognito profile that can only be set during an incognito session and is deleted when the incognito session ends (overrides regular and incognito_persistent preferences).
Enum
"regular", "regular_only", "incognito_persistent", or "incognito_session_only"

LevelOfControl

One of
  • not_controllable: cannot be controlled by any extension
  • controlled_by_other_extensions: controlled by extensions with higher precedence
  • controllable_by_this_extension: can be controlled by this extension
  • controlled_by_this_extension: controlled by this extension
Enum
"not_controllable", "controlled_by_other_extensions", "controllable_by_this_extension", or "controlled_by_this_extension"

ChromeSetting

An interface that allows access to a Chrome browser setting. See accessibilityFeatures for an example.

onChange

Fired after the setting changes.

methods

get

ChromeSetting.get(object details, function callback)

Gets the value of a setting.

Parameters
object details

Which setting to consider.

boolean (optional) incognito

Whether to return the value that applies to the incognito session (default false).

function callback

The callback parameter should be a function that looks like this:

function(object details) {...};
object details

Details of the currently effective value.

any value

The value of the setting.

enum of "not_controllable", "controlled_by_other_extensions", "controllable_by_this_extension", or "controlled_by_this_extension" levelOfControl

The level of control of the setting.

boolean (optional) incognitoSpecific

Whether the effective value is specific to the incognito session.
This property will only be present if the incognito property in the details parameter of get() was true.

set

ChromeSetting.set(object details, function callback)

Sets the value of a setting.

Parameters
object details

Which setting to change.

any value

The value of the setting.
Note that every setting has a specific value type, which is described together with the setting. An extension should not set a value of a different type.

enum of "regular", "regular_only", "incognito_persistent", or "incognito_session_only" (optional) scope

Where to set the setting (default: regular).

function (optional) callback

Called at the completion of the set operation.

If you specify the callback parameter, it should be a function that looks like this:

function() {...};

clear

ChromeSetting.clear(object details, function callback)

Clears the setting, restoring any default value.

Parameters
object details

Which setting to clear.

enum of "regular", "regular_only", "incognito_persistent", or "incognito_session_only" (optional) scope

Where to clear the setting (default: regular).

function (optional) callback

Called at the completion of the clear operation.

If you specify the callback parameter, it should be a function that looks like this:

function() {...};
events

addListener

onChange.addListener(function callback)
Parameters
function callback

The callback parameter should be a function that looks like this:

function(object details) {...};
object details
any value

The value of the setting after the change.

enum of "not_controllable", "controlled_by_other_extensions", "controllable_by_this_extension", or "controlled_by_this_extension" levelOfControl

The level of control of the setting.

boolean (optional) incognitoSpecific

Whether the value that has changed is specific to the incognito session.
This property will only be present if the user has enabled the extension in incognito mode.