display up button in key transfer activity

k9mail/src/main/java/com/fsck/k9/ui/endtoend/AutocryptKeyTransferActivity.kt

@@ -9,6 +9,7 @@ import android.os.Build
 import android.os.Bundle
 import android.transition.TransitionInflater
 import android.transition.TransitionManager
+import android.view.MenuItem
 import android.view.View
 import com.fsck.k9.R
 import com.fsck.k9.activity.K9Activity
@@ -30,12 +31,23 @@ class AutocryptKeyTransferActivity : K9Activity() {
 
         val accountUuid = intent.getStringExtra(EXTRA_ACCOUNT)
 
+        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
+
         transferSendButton.setOnClickListener { presenter.onClickTransferSend() }
         transferButtonShowCode.setOnClickListener { presenter.onClickShowTransferCode() }
 
         presenter.initFromIntent(accountUuid)
     }
 
+    override fun onOptionsItemSelected(item: MenuItem?): Boolean {
+        if (item?.itemId == android.R.id.home) {
+            presenter.onClickHome();
+            return true
+        } else {
+            return super.onOptionsItemSelected(item)
+        }
+    }
+
     fun setAddress(address: String) {
         transferAddress1.text = address
         transferAddress2.text = address
@@ -132,6 +144,11 @@ class AutocryptKeyTransferActivity : K9Activity() {
         }
     }
 
+    fun finishAsCancelled() {
+        setResult(RESULT_CANCELED)
+        finish()
+    }
+
     companion object {
         private const val EXTRA_ACCOUNT = "account"
 

k9mail/src/main/java/com/fsck/k9/ui/endtoend/AutocryptKeyTransferPresenter.kt

@@ -60,6 +60,10 @@ class AutocryptKeyTransferPresenter internal constructor(
         viewModel.autocryptSetupTransferLiveEvent.recall()
     }
 
+    fun onClickHome() {
+        view.finishAsCancelled()
+    }
+
     fun onClickTransferSend() {
         view.sceneGeneratingAndSending()