Enable EMERGENCY mobile connections.

Hooks the ConnectivityManager.TYPE_MOBILE_EMERGENCY,
PhoneConstants.APN_TYPE_EMERGENCY, and NetworkCapabilities.NET_CAPABILITY_EIMS
together so carrier apps can request connections to this APN.

bug:21785357
Change-Id: Id92a5e28d19407cc7a8f8b5478b23457f2f7f89d
diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 12cd5f1..e848611 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -432,7 +432,8 @@
     public static final int TYPE_MOBILE_IA = 14;
 
     /**
-     * Emergency PDN connection for emergency calls
+     * Emergency PDN connection for emergency services.  This
+     * may include IMS and MMS in emergency situations.
      * {@hide}
      */
     public static final int TYPE_MOBILE_EMERGENCY = 15;
diff --git a/core/java/android/net/NetworkCapabilities.java b/core/java/android/net/NetworkCapabilities.java
index 658051c..514d24a 100644
--- a/core/java/android/net/NetworkCapabilities.java
+++ b/core/java/android/net/NetworkCapabilities.java
@@ -133,7 +133,8 @@
 
     /**
      * Indicates this is a network that has the ability to reach a carrier's
-     * Emergency IMS servers, used for network signaling during emergency calls.
+     * Emergency IMS servers or other services, used for network signaling
+     * during emergency calls.
      */
     public static final int NET_CAPABILITY_EIMS           = 10;
 
diff --git a/telephony/java/com/android/internal/telephony/PhoneConstants.java b/telephony/java/com/android/internal/telephony/PhoneConstants.java
index 2a4032c..572cc6f 100644
--- a/telephony/java/com/android/internal/telephony/PhoneConstants.java
+++ b/telephony/java/com/android/internal/telephony/PhoneConstants.java
@@ -133,7 +133,8 @@
     public static final String APN_TYPE_CBS = "cbs";
     /** APN type for IA Initial Attach APN */
     public static final String APN_TYPE_IA = "ia";
-    /** APN type for IA Emergency PDN */
+    /** APN type for Emergency PDN. This is not an IA apn, but is used
+     * for access to carrier services in an emergency call situation. */
     public static final String APN_TYPE_EMERGENCY = "emergency";
 
     public static final int RIL_CARD_MAX_APPS    = 8;