Merge "Clear the preferred top focusable root task when moving" into tm-qpr-dev

        // wasContained} restricts the preferred root task is set only when moving an existing

        // root task to top instead of adding a new root task that may be too early (e.g. in the

        // middle of launching or reparenting).

        if (moveToTop && child.isFocusableAndVisible()) {

            mPreferredTopFocusableRootTask = child;

        final boolean isTopFocusableTask = moveToTop && child.isTopActivityFocusable();

        if (isTopFocusableTask) {

            mPreferredTopFocusableRootTask =

                    child.shouldBeVisible(null /* starting */) ? child : null;

        } else if (mPreferredTopFocusableRootTask == child) {

            mPreferredTopFocusableRootTask = null;

        }