Add a hidden telephony API for querying SIM derived locales.

bug: 19818550
Change-Id: Ide6c05ad8fe7b0cff6f20ddfe755e83e9b3a21aa

telephony/java/android/telephony/TelephonyManager.java

@@ -4580,4 +4580,18 @@ public class TelephonyManager {
         } catch (RemoteException e) {
         }
     }
+
+
+    /** @hide */
+    public String getLocaleFromDefaultSim() {
+        try {
+            final ITelephony telephony = getITelephony();
+            if (telephony != null) {
+                return telephony.getLocaleFromDefaultSim();
+            }
+        } catch (RemoteException ex) {
+        }
+
+        return null;
+    }
 }

telephony/java/com/android/internal/telephony/ITelephony.aidl

@@ -945,4 +945,12 @@ interface ITelephony {
     int getSubIdForPhoneAccount(in PhoneAccount phoneAccount);
 
     void factoryReset(int subId);
+
+    /**
+     * An estimate of the users's current locale based on the default SIM.
+     *
+     * The returned string will be a well formed BCP-47 language tag, or {@code null}
+     * if no locale could be derived.
+     */
+    String getLocaleFromDefaultSim();
 }