Export ServiceState#DataRegState into TelephonyProvider

Add test case to make sure notifyChange was called by
notifyChangeForSubId and notifyChangeForSubIdAndField
when dataRegState changes.

Bug: 182601774
Test: atest com.android.phone.ServiceStateProviderTest
Change-Id: I30f4b3f53daa311ef2526b9f5aceed2099df6da0
diff --git a/src/com/android/phone/ServiceStateProvider.java b/src/com/android/phone/ServiceStateProvider.java
index 13d1c3a..32562fa 100644
--- a/src/com/android/phone/ServiceStateProvider.java
+++ b/src/com/android/phone/ServiceStateProvider.java
@@ -19,6 +19,7 @@
 import static android.provider.Telephony.ServiceStateTable;
 import static android.provider.Telephony.ServiceStateTable.CONTENT_URI;
 import static android.provider.Telephony.ServiceStateTable.DATA_NETWORK_TYPE;
+import static android.provider.Telephony.ServiceStateTable.DATA_REG_STATE;
 import static android.provider.Telephony.ServiceStateTable.DUPLEX_MODE;
 import static android.provider.Telephony.ServiceStateTable.IS_MANUAL_NETWORK_SELECTION;
 import static android.provider.Telephony.ServiceStateTable.VOICE_REG_STATE;
@@ -63,18 +64,6 @@
     public static final String SERVICE_STATE = "service_state";
 
     /**
-     * An integer value indicating the current data service state.
-     * <p>
-     * Valid values: {@link ServiceState#STATE_IN_SERVICE},
-     * {@link ServiceState#STATE_OUT_OF_SERVICE}, {@link ServiceState#STATE_EMERGENCY_ONLY},
-     * {@link ServiceState#STATE_POWER_OFF}.
-     * <p>
-     * This is the same as {@link ServiceState#getDataRegState()}.
-     * @hide
-     */
-    public static final String DATA_REG_STATE = "data_reg_state";
-
-    /**
      * An integer value indicating the current voice roaming type.
      * <p>
      * This is the same as {@link ServiceState#getVoiceRoamingType()}.