Revert "Return null for contacts local account"

This reverts commit 56b28d4ad7.
Reverting because partners are concerned about backwards compatibility.

Bug: 188347648
Test: m droid

Change-Id: I84862cbc3e6d991743b27beca20d0c6b6456e02e

core/java/android/provider/ContactsContract.java

@@ -2956,7 +2956,10 @@ public final class ContactsContract {
          */
         @Nullable
         public static String getLocalAccountName(@NonNull Context context) {
-            return null;
+            //  config_rawContactsLocalAccountName is defined in
+            //  platform/frameworks/base/core/res/res/values/config.xml
+            return TextUtils.nullIfEmpty(context.getString(
+                    com.android.internal.R.string.config_rawContactsLocalAccountName));
         }
 
         /**
@@ -2972,7 +2975,10 @@ public final class ContactsContract {
          */
         @Nullable
         public static String getLocalAccountType(@NonNull Context context) {
-            return null;
+            //  config_rawContactsLocalAccountType is defined in
+            //  platform/frameworks/base/core/res/res/values/config.xml
+            return TextUtils.nullIfEmpty(context.getString(
+                    com.android.internal.R.string.config_rawContactsLocalAccountType));
         }
 
         /**