Only handle transition requests in split if active and visible

- Otherwise handling all requests prevents dynamic remote animations from being registered and run

Fixes: 285995223
Test: Presubmit
Change-Id: Ic5d3d197a1d9623d1eb5612dcfb4fecd83666145

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java

@@ -2342,6 +2342,11 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                     prepareExitSplitScreen(STAGE_TYPE_UNDEFINED, out);
                 }
             }
+
+            // When split in the background, it should be only opening/dismissing transition and
+            // would keep out not empty. Prevent intercepting all transitions for split screen when
+            // it is in the background and not identify to handle it.
+            return (!out.isEmpty() || isSplitScreenVisible()) ? out : null;
         } else {
             if (isOpening && getStageOfTask(triggerTask) != null) {
                 // One task is appearing into split, prepare to enter split screen.
@@ -2351,8 +2356,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                 mSplitTransitions.setEnterTransition(transition, request.getRemoteTransition(),
                         TRANSIT_SPLIT_SCREEN_PAIR_OPEN, !mIsDropEntering);
             }
+            return out;
         }
-        return out;
     }
 
     /**