Computer Configuration > Administrative Templates > Google Chrome - Default Settings (users can override)
Both
HKLM\Software\Policies\Google\Chrome\Recommended
Enables the use of a default search provider on the context menu. If you set this policy to disabled the search context menu item that relies on your default search provider will not be available. If this policy is set to enabled or not set, the context menu item for your default search provider will be available. The policy value is only appled when the DefaultSearchProviderEnabled policy is enabled, and is not applicable otherwise.