Bluetooth : fix for handling back key during pair dialog display

- Pressing back key when pairing dialog appears infront , device shows "Pairing..."
  if we don't have any bonded device in device list.
- when press back key will perform onCancel() operation.

Change-Id: Iacd654efad455f17a5c3bb09f822d9af5a7aed7d
Signed-off-by: jhtop.kim <jhtop.kim@samsung.com>

src/com/android/settings/bluetooth/BluetoothPairingDialog.java

@@ -41,6 +41,7 @@ import android.widget.TextView;
 import com.android.internal.app.AlertActivity;
 import com.android.internal.app.AlertController;
 import com.android.settings.R;
+import android.view.KeyEvent;
 
 /**
  * BluetoothPairingDialog asks the user to enter a PIN / Passkey / simple confirmation
@@ -340,6 +341,13 @@ public final class BluetoothPairingDialog extends AlertActivity implements
         mDevice.cancelPairingUserInput();
     }
 
+    public boolean onKeyDown(int keyCode, KeyEvent event) {
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            onCancel();
+        }
+        return super.onKeyDown(keyCode,event);
+    }
+
     public void onClick(DialogInterface dialog, int which) {
         switch (which) {
             case BUTTON_POSITIVE: