Snapshot 2 tasks when swipe up split case

Swipe up snapshot only capture the top one task, but for split
screen case it should capture two tasks otherwise the snapshot
in overview would be empty in some cases.

Fix: 247420799
Test: manual
Test: pass existing tests
Change-Id: I3acd477eaca3cb98d86e2446dbb2dbd6295c687d

quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java

@@ -1835,6 +1835,17 @@ public abstract class AbsSwipeUpHandler<T extends StatefulActivity<S>,
                         if (mRecentsAnimationController == null) return;
                         final ThumbnailData taskSnapshot =
                                 mRecentsAnimationController.screenshotTask(runningTaskId);
+                        // If split case, we should update all split tasks snapshot
+                        if (mIsSwipeForSplit) {
+                            int[] splitTaskIds = TopTaskTracker.INSTANCE.get(
+                                    mContext).getRunningSplitTaskIds();
+                            for (int i = 0; i < splitTaskIds.length; i++) {
+                                // Skip running one because done above.
+                                if (splitTaskIds[i] == runningTaskId) continue;
+
+                                mRecentsAnimationController.screenshotTask(splitTaskIds[i]);
+                            }
+                        }
                         MAIN_EXECUTOR.execute(() -> {
                             mTaskSnapshot = taskSnapshot;
                             if (!updateThumbnail(runningTaskId, false /* refreshView */)) {