A new page has been created for viewing assets. This replaces the old
`selectedToken` state, which previously would augment the home page
to show token-specific information.
The new asset page shows the standard token overview as seen previously
on the home page, plus a history filtered to show just transactions
relevant to that token.
The actions that were available in the old token list menu have been
moved to a "Token Options" menu that mirrors the "Account Options"
menu.
The `selectedTokenAddress` state has been removed, as it is no longer
being used for anything.
`getMetaMetricState` has been renamed to `getBackgroundMetaMetricState`
because its sole purpose is extracting data from the background state
to send metrics from the background. It's not really a selector, but
it was convenient for it to use the same selectors the UI uses to
extract background data, so I left it there for now.
A new Redux store has been added to track state related to browser history.
The most recent "overview" page (i.e. the home page or the asset page) is
currently being tracked, so that actions taken from the asset page can return
the user back to the asset page when the action has finished.
An alert is now shown when the user switches from an account that is
connected to the active tab to an account that is not connected. The
alert prompts the user to dismiss the alert or connect the account
they're switching to.
The "loading" state is handled by disabling the buttons, and the error
state is handled by displaying a generic error message and disabling
the connect button.
The new reducer for this alert has been created with `createSlice` from
the Redux Toolkit. This utility is recommended by the Redux team, and
represents a new style of writing reducers that I hope we will use more
in the future (or at least something similar). `createSlice` constructs
a reducer, actions, and action creators automatically. The reducer is
constructed using their `createReducer` helper, which uses Immer to
allow directly mutating the state in the reducer but exposing these
changes as immutable.
The `transForward` app state is no longer used, so it has been removed.
Associated actions have been removed as well.
This state dates back a few years, so I was unable to determine when it
was made obsolete.
This state hasn't been used since #5886. The nonce we display in our UI
is now from the background, rather than queried directly from the
front-end.
This also means we save making this network call each time a pending
transaction is added, and each time the transaction list is mounted.
The "global" action constants (the ones previously in `actions.js`)
have been moved to a separate module. This was necessary to avoid a
circular dependency in an upcoming change that was causing problems.
In general the "ducks" pattern of organizing Redux stores does result
in circular dependency problems. This is because reuse of actions
between reducers is encouraged, so it's not uncommon for two reducers
to want to reference an action from the other. Going forward we can
avoid this problem by moving action constants that are shared between
reducers into this shared module.
