Rewriting phone constants for mainline

* Exposing Emergency extra constants through TelephonyManager
* Always reading or writing PhoneConstants.SubscriptionKey
with SubscriptionManager.EXTRA_SUBSCRIPTION_KEY

Bug: 147465477
Test: TeleServiceTests
Change-Id: I9cf495f19f3a752459ed67aa21bf6e0510a66547
diff --git a/src/com/android/phone/EmergencyCallbackModeService.java b/src/com/android/phone/EmergencyCallbackModeService.java
index 41d83c4..7e68255 100644
--- a/src/com/android/phone/EmergencyCallbackModeService.java
+++ b/src/com/android/phone/EmergencyCallbackModeService.java
@@ -31,6 +31,7 @@
 import android.os.IBinder;
 import android.os.Message;
 import android.sysprop.TelephonyProperties;
+import android.telephony.TelephonyManager;
 import android.util.Log;
 
 import com.android.internal.telephony.Phone;
@@ -119,7 +120,7 @@
             // Stop the service when phone exits Emergency Callback Mode
             if (intent.getAction().equals(
                     TelephonyIntents.ACTION_EMERGENCY_CALLBACK_MODE_CHANGED)) {
-                if (intent.getBooleanExtra("phoneinECMState", false) == false) {
+                if (!intent.getBooleanExtra(TelephonyManager.EXTRA_PHONE_IN_ECM_STATE, false)) {
                     stopSelf();
                 }
             }