Merge "Do not crash when trying to sleep non-existent display" into main

                groupIds = mDisplayManagerInternal.getDisplayGroupIds();

            } else {

                DisplayInfo displayInfo = mDisplayManagerInternal.getDisplayInfo(displayId);

                Preconditions.checkArgument(displayInfo != null, "display ID(%d) doesn't exist",

                        displayId);

                if (displayInfo == null) {

                    Slog.w(TAG, "Can not sleep non-existent display ID " + displayId);

                    return;

                }

                int groupId = displayInfo.displayGroupId;

                if (groupId == Display.INVALID_DISPLAY_GROUP) {

                    throw new IllegalArgumentException("invalid display group ID");