Add method in Phone interface to check whether data is enabled.

This adds isDataConnectivityEnabled to allow test methods to query the
data connectivity state.

telephony/java/com/android/internal/telephony/Phone.java

@@ -1265,6 +1265,13 @@ public interface Phone {
      */
     boolean disableDataConnectivity();
 
+    /**
+     * Report the current state of data connectivity (enabled or disabled)
+     * @return {@code false} if data connectivity has been explicitly disabled,
+     * {@code true} otherwise.
+     */
+    boolean isDataConnectivityEnabled();
+
     /**
      * Enables the specified APN type. Only works for "special" APN types,
      * i.e., not the default APN.

telephony/java/com/android/internal/telephony/PhoneProxy.java

@@ -614,6 +614,10 @@ public class PhoneProxy extends Handler implements Phone {
         return mActivePhone.disableApnType(type);
     }
 
+    public boolean isDataConnectivityEnabled() {
+        return mActivePhone.isDataConnectivityEnabled();
+    }
+
     public boolean isDataConnectivityPossible() {
         return mActivePhone.isDataConnectivityPossible();
     }

telephony/java/com/android/internal/telephony/cdma/CDMAPhone.java

@@ -508,6 +508,10 @@ public class CDMAPhone extends PhoneBase {
         return false;
     }
 
+    public boolean isDataConnectivityEnabled() {
+        return mDataConnection.getDataEnabled();
+    }
+
     public boolean isDataConnectivityPossible() {
         boolean noData = mDataConnection.getDataEnabled() &&
                 getDataConnectionState() == DataState.DISCONNECTED;

telephony/java/com/android/internal/telephony/gsm/GSMPhone.java

@@ -1169,6 +1169,10 @@ public class GSMPhone extends PhoneBase {
         return mDataConnection.getDnsServers(apnType);
     }
 
+    public boolean isDataConnectivityEnabled() {
+        return mDataConnection.getDataEnabled();
+    }
+
     /**
      * The only circumstances under which we report that data connectivity is not
      * possible are