revert a bit to please some tests

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/androidx/WorkflowLifecycleOwner.kt

@@ -8,8 +8,6 @@ import androidx.annotation.VisibleForTesting
 import androidx.annotation.VisibleForTesting.Companion.PRIVATE
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.Lifecycle.Event
-import androidx.lifecycle.Lifecycle.Event.ON_DESTROY
-import androidx.lifecycle.Lifecycle.Event.ON_PAUSE
 import androidx.lifecycle.Lifecycle.State.DESTROYED
 import androidx.lifecycle.Lifecycle.State.INITIALIZED
 import androidx.lifecycle.Lifecycle.State.RESUMED
@@ -192,44 +190,69 @@ internal class RealWorkflowLifecycleOwner(
       oldLifecycle?.removeObserver(this)
       parentLifecycle?.addObserver(this)
     }
-    updateLifecycle(Event.ON_START)
+    updateLifecycle(Event.ON_RESUME)
   }
 
   override fun onViewDetachedFromWindow(v: View) {
     viewIsAttachedToWindow = false
-    updateLifecycle(ON_PAUSE)
+    updateLifecycle(Event.ON_PAUSE)
   }
 
   /** Called when the [parentLifecycle] changes state. */
   override fun onStateChanged(
     source: LifecycleOwner,
     event: Event
   ) {
-    // we should always consume what the new event is from onStateChanged. if we try to
-    // assume the event like we did in the past, we can get into scenarios where we try to put
-    // a view in created, when it's parent hasn't completed fully it's super.onCreate yet.
     updateLifecycle(event)
   }
 
   override fun destroyOnDetach() {
     if (!destroyOnDetach) {
       destroyOnDetach = true
-      updateLifecycle(Event.ON_DESTROY)
+      updateLifecycle()
     }
   }
 
   @VisibleForTesting(otherwise = PRIVATE)
-  internal fun updateLifecycle(event: Event) {
-    val targetState = event.targetState
+  internal fun updateLifecycle(event: Event? = null) {
+    val parentState = parentLifecycle?.currentState
+    val localState = localLifecycle.currentState
 
-    if (localLifecycle.currentState == DESTROYED || hasBeenDestroyed) {
+    if (localState == DESTROYED || hasBeenDestroyed) {
       view = null
       // Local lifecycle is in a terminal state.
       return
     }
 
-    localLifecycle.currentState = targetState
-    targetState.let { newState ->
+    localLifecycle.currentState = when {
+      event != null -> {
+        event.targetState
+      }
+      destroyOnDetach && !viewIsAttachedToWindow -> {
+        // We've been enqueued for destruction.
+        // Stay attached to the parent's lifecycle until we re-attach, since the parent could be
+        // destroyed while we're detached.
+        DESTROYED
+      }
+      parentState != null -> {
+        // We may or may not be attached, but we have a parent lifecycle so we just blindly follow
+        // it.
+        parentState
+      }
+      localState == INITIALIZED -> {
+        // We have no parent and we're not destroyed, which means we have never been attached, so
+        // the only valid state we can be in is INITIALIZED.
+        INITIALIZED
+      }
+      else -> {
+        // We don't have a parent and we're neither in DESTROYED or INITIALIZED: this is an invalid
+        // state. Throw an AssertionError instead of IllegalStateException because there's no API to
+        // get into this state, so this means the library has a bug.
+        throw AssertionError(
+          "Must have a parent lifecycle after attaching and until being destroyed."
+        )
+      }
+    }.let { newState ->
       if (newState == DESTROYED) {
         hasBeenDestroyed = true
 
@@ -253,7 +276,7 @@ internal class RealWorkflowLifecycleOwner(
         // out of the INITIALIZED state. That's an invalid state transition, and so setCurrentState
         // will throw if we do that. That exception can mask actual test failures, so to avoid that
         // here we just stay in the initialized state forever.
-        if (localLifecycle.currentState == INITIALIZED) {
+        if (localState == INITIALIZED) {
           INITIALIZED
         } else {
           DESTROYED