Enable presence check at application level using

RawTagConnection.isConnected() method.

Also needs packages/apps/Nfc to be updated.

Change-Id: I726e88853e2c4b348f3b87b7574bc6eded7f5b7c
Signed-off-by: Nick Pelly <npelly@google.com>

core/java/android/nfc/INfcTag.aidl

@@ -28,6 +28,7 @@ interface INfcTag
     String getType(int nativeHandle);
     byte[] getUid(int nativeHandle);
     boolean isNdef(int nativeHandle);
+    boolean isPresent(int nativeHandle);
     byte[] transceive(int nativeHandle, in byte[] data);
 
     int getLastError(int nativeHandle);

core/java/android/nfc/RawTagConnection.java

@@ -95,10 +95,16 @@ public class RawTagConnection {
      * returns true.
      */
     public boolean isConnected() {
-        // TODO(nxp): update mIsConnected when tag goes out of range -
-        //            but do not do an active prescence check in
-        //            isConnected()
-        return mIsConnected;
+        if (!mIsConnected) {
+            return false;
+        }
+
+        try {
+            return mTagService.isPresent(mTag.mNativeHandle);
+        } catch (RemoteException e) {
+            Log.e(TAG, "NFC service died", e);
+            return false;
+        }
     }
 
     /**