metamask-extension/app/scripts/migrations/049.js

import { cloneDeep } from 'lodash'

const version = 49

/**
 * Migrate metaMetrics state to the new MetaMetrics controller
 */
export default {
  version,
  async migrate(originalVersionedData) {
    const versionedData = cloneDeep(originalVersionedData)
    versionedData.meta.version = version
    const state = versionedData.data
    versionedData.data = transformState(state)
    return versionedData
  },
}

function transformState(state = {}) {
  if (state.PreferencesController) {
    const {
      metaMetricsId,
      participateInMetaMetrics,
      metaMetricsSendCount,
    } = state.PreferencesController
    state.MetaMetricsController = state.MetaMetricsController ?? {}

    if (metaMetricsId !== undefined) {
      state.MetaMetricsController.metaMetricsId = metaMetricsId
      delete state.PreferencesController.metaMetricsId
    }

    if (participateInMetaMetrics !== undefined) {
      state.MetaMetricsController.participateInMetaMetrics = participateInMetaMetrics
      delete state.PreferencesController.participateInMetaMetrics
    }

    if (metaMetricsSendCount !== undefined) {
      state.MetaMetricsController.metaMetricsSendCount = metaMetricsSendCount
      delete state.PreferencesController.metaMetricsSendCount
    }
  }
  return state
}