chrome.types

Description
The chrome.types API contains type declarations for Chrome.

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.

System settings provided by the operating system
Command-line parameters
Settings provided by extensions
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
ChromeSetting
ChromeSettingScope
LevelOfControl

Types

ChromeSetting

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

Properties

onChange
events.Event<function>
Fired after the setting changes.
Add a listener like this:
onChange.addListener(listener)
- listener
  function
  The listener parameter should be a function that looks like this:
  (details: object) => {...}
  details
  object
  incognitoSpecific
  boolean optional
  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.
  levelOfControl
  fontSettings.LevelOfControl
  The level of control of the setting.
  value
  T
  The value of the setting after the change.
clear
function
Clears the setting, restoring any default value.
The clear function looks like this:
clear(details: object, callback: function) => {...}
- details
  object
  Which setting to clear.
  scope
  ChromeSettingScope optional
  Where to clear the setting (default: regular).
- callback
  function
  Called at the completion of the clear operation.
  The callback parameter should be a function that looks like this:
  () => {...}
get
function
Gets the value of a setting.
The get function looks like this:
get(details: object, callback: function) => {...}
- details
  object
  Which setting to consider.
  incognito
  boolean optional
  Whether to return the value that applies to the incognito session (default false).
- callback
  function
  The callback parameter should be a function that looks like this:
  (details: object) => {...}
  details
  object
  Details of the currently effective value.
  incognitoSpecific
  boolean optional
  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.
  levelOfControl
  fontSettings.LevelOfControl
  The level of control of the setting.
  value
  T
  The value of the setting.
set
function
Sets the value of a setting.
The set function looks like this:
set(details: object, callback: function) => {...}
- details
  object
  Which setting to change.
  scope
  ChromeSettingScope optional
  Where to set the setting (default: regular).
  value
  T
  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.
- callback
  function
  Called at the completion of the set operation.
  The callback parameter should be a function that looks like this:
  () => {...}

ChromeSettingScope

Since Chrome 44.

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

Since Chrome 44.

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"