Merge #4798

4798: Set parentId to session before adding tab r=csadilek a=mawen7
Co-authored-by: mawen7 <mawen7@users.noreply.github.com>

components/browser/session/src/main/java/mozilla/components/browser/session/LegacySessionManager.kt

@@ -158,13 +158,6 @@ class LegacySessionManager(
 
         if (parent != null) {
             val parentIndex = values.indexOf(parent)
-
-            if (parentIndex == -1) {
-                throw IllegalArgumentException("The parent does not exist")
-            }
-
-            session.parentId = parent.id
-
             values.add(parentIndex + 1, session)
         } else {
             if (viaRestore) {

components/browser/session/src/main/java/mozilla/components/browser/session/SessionManager.kt

@@ -134,6 +134,11 @@ class SessionManager(
     ) {
         // Add store to Session so that it can dispatch actions whenever it changes.
         session.store = store
+        if (parent != null) {
+            require(all.contains(parent)) { "The parent does not exist" }
+            session.parentId = parent.id
+        }
+
         if (session.isCustomTabSession()) {
             store?.syncDispatch(
                 CustomTabListAction.AddCustomTabAction(