Merge "Exit split if one of the split is empty" into udc-dev

                }

            }

            if (mMainStage.getChildCount() == 0 || mSideStage.getChildCount() == 0) {

                // TODO(shell-transitions): Implement a fallback behavior for now.

                throw new IllegalStateException("Somehow removed the last task in a stage"

                        + " outside of a proper transition");

                Log.e(TAG, "Somehow removed the last task in a stage outside of a proper "

                        + "transition.");

                final WindowContainerTransaction wct = new WindowContainerTransaction();

                final int dismissTop = mMainStage.getChildCount() == 0

                        ? STAGE_TYPE_MAIN : STAGE_TYPE_SIDE;

                prepareExitSplitScreen(dismissTop, wct);

                mSplitTransitions.startDismissTransition(wct, this, dismissTop,

                        EXIT_REASON_UNKNOWN);

                // This can happen in some pathological cases. For example:

                // 1. main has 2 tasks [Task A (Single-task), Task B], side has one task [Task C]

                // 2. Task B closes itself and starts Task A in LAUNCH_ADJACENT at the same time