Make new task follow source task root

For current split UX, we want new task launched by old task can
stay in split. To achieve this, add a rule if source task's root
task is created by organizer then use it as root task of new task.

Bug: 202740040
Test: manual
Test: pass existing tests
Change-Id: Ibcbf3c4f78607a9ca44eee29c4c078daf1c46402

services/core/java/com/android/server/wm/ActivityStarter.java

@@ -2737,9 +2737,11 @@ class ActivityStarter {
         // If it exist, we need to reparent target root task from TDA to launch root task.
         final TaskDisplayArea tda = mTargetRootTask.getDisplayArea();
         final Task launchRootTask = tda.getLaunchRootTask(mTargetRootTask.getWindowingMode(),
-                mTargetRootTask.getActivityType(), null /** options */, null /** sourceTask */,
-                0 /** launchFlags */);
-        if (launchRootTask != null && launchRootTask != mTargetRootTask) {
+                mTargetRootTask.getActivityType(), null /** options */,
+                mSourceRootTask, 0 /** launchFlags */);
+        // If target root task is created by organizer, let organizer handle reparent itself.
+        if (!mTargetRootTask.mCreatedByOrganizer && launchRootTask != null
+                && launchRootTask != mTargetRootTask) {
             mTargetRootTask.reparent(launchRootTask, POSITION_TOP);
             mTargetRootTask = launchRootTask;
         }

services/core/java/com/android/server/wm/TaskDisplayArea.java

@@ -1275,6 +1275,11 @@ final class TaskDisplayArea extends DisplayArea<WindowContainer> {
                 }
             }
         }
+        // For better split UX, If task launch by the source task which root task is created by
+        // organizer, it should also launch in that root too.
+        if (sourceTask != null && sourceTask.getRootTask().mCreatedByOrganizer) {
+            return sourceTask.getRootTask();
+        }
         return null;
     }