This is part of the effort to consolidate keyring interactions between extension and mobile.
Originally proposed here.

Context

In the extension, ledgerKeyring.destroy and trezorKeyring.dispose methods are called to lock hardware keyrings, before calling EthKeyringController ’s setLocked method.

Solution

EthKeyringController should be responsible for calling an optional keyring.destroy() method when a reference to a keyring is being dropped (lock, removeAccount)

Task list

• Make changes to EthKeyringController
• Release new version of EthKeyringController
• Use new version of EthKeyringController in KeyringController