Merge "don't call the reparent method when the old parent of task is removed." into main

        activityIdleInternal(null /* idleActivity */, false /* fromTimeout */,

                true /* processPausingActivities */, null /* configuration */);

        if (rootTask.getParent() == null) {

            // The activities in the task may already be finishing. Then the task could be removed

            // when performing the idle check.

            return;

        }

        // Reparent all the tasks to the bottom of the display

        final DisplayContent toDisplay =

                mRootWindowContainer.getDisplayContent(DEFAULT_DISPLAY);