Add APIs to getDefaultDialerPackage and getSystemDialerPackage

getDefaultDialerPackage is a public API and will be used by
apps to determine if they are the default dialer.

getSystemDialerPackage is a hidden API and is only used by
system components.

Also add new public string constants to allow apps to show
a dialog requesting that the user change the current default
dialer.

Bug: 20304458
Change-Id: I121d36741474c1fe171c372fb766a6c128228c9c
diff --git a/telecomm/java/com/android/internal/telecom/ITelecomService.aidl b/telecomm/java/com/android/internal/telecom/ITelecomService.aidl
index 45b2482..49f2aad 100644
--- a/telecomm/java/com/android/internal/telecom/ITelecomService.aidl
+++ b/telecomm/java/com/android/internal/telecom/ITelecomService.aidl
@@ -137,6 +137,16 @@
      */
     ComponentName getDefaultPhoneApp();
 
+    /**
+     * @see TelecomServiceImpl#getDefaultDialerPackage
+     */
+    String getDefaultDialerPackage();
+
+    /**
+     * @see TelecomServiceImpl#getSystemDialerPackage
+     */
+    String getSystemDialerPackage();
+
     //
     // Internal system apis relating to call management.
     //