DMD: Support minimum refresh rate

Bug: 139685237
Change-Id: Ib41dee351276d70733fffa18620455e4e6f9ddfc
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index aee178a..0060741 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -93,6 +93,7 @@
                     Settings.System.VOLUME_VOICE, // deprecated since API 2?
                     Settings.System.WHEN_TO_MAKE_WIFI_CALLS, // bug?
                     Settings.System.WINDOW_ORIENTATION_LISTENER_LOG, // used for debugging only
+                    Settings.System.MIN_REFRESH_RATE, // depends on hardware capabilities
                     Settings.System.PEAK_REFRESH_RATE // depends on hardware capabilities
                     );