metamask-extension/ui/app/pages/first-time-flow/onboarding-initiator-util.js

import extension from 'extensionizer'
import log from 'loglevel'

const returnToOnboardingInitiatorTab = async (onboardingInitiator) => {
  const tab = await (new Promise((resolve) => {
    extension.tabs.update(onboardingInitiator.tabId, { active: true }, (tab) => {
      if (tab) {
        resolve(tab)
      } else {
        // silence console message about unchecked error
        if (extension.runtime.lastError) {
          log.debug(extension.runtime.lastError)
        }
        resolve()
      }
    })
  }))

  if (!tab) {
    // this case can happen if the tab was closed since being checked with `extension.tabs.get`
    log.warn(`Setting current tab to onboarding initiator has failed; falling back to redirect`)
    window.location.assign(onboardingInitiator.location)
  } else {
    window.close()
  }
}

export const returnToOnboardingInitiator = async (onboardingInitiator) => {
  const tab = await (new Promise((resolve) => {
    extension.tabs.get(onboardingInitiator.tabId, (tab) => {
      if (tab) {
        resolve(tab)
      } else {
        // silence console message about unchecked error
        if (extension.runtime.lastError) {
          log.debug(extension.runtime.lastError)
        }
        resolve()
      }
    })
  }))

  if (tab) {
    await returnToOnboardingInitiatorTab(onboardingInitiator)
  } else {
    window.location.assign(onboardingInitiator.location)
  }
}