Should not decode Wi-Fi QR code after onPause

Bug: 130141694
Test: manual
      atest WifiDppQrCodeScannerFragmentTest

Change-Id: I412fb7c06220c23bddc7b3c448fcc72a00bdecc3

src/com/android/settings/wifi/dpp/WifiDppQrCodeScannerFragment.java

@@ -47,6 +47,7 @@ import android.widget.TextView;
 
 import androidx.annotation.StringRes;
 import androidx.annotation.UiThread;
+import androidx.annotation.VisibleForTesting;
 import androidx.lifecycle.ViewModelProviders;
 
 import com.android.settings.R;
@@ -261,6 +262,24 @@ public class WifiDppQrCodeScannerFragment extends WifiDppQrCodeBaseFragment impl
         });
     }
 
+    @Override
+    public void onPause() {
+        if (mCamera != null) {
+            mCamera.stop();
+        }
+
+        super.onPause();
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+
+        if (!isGoingInitiator()) {
+            restartCamera();
+        }
+    }
+
     @Override
     public int getMetricsCategory() {
         if (mIsConfiguratorMode) {
@@ -702,4 +721,9 @@ public class WifiDppQrCodeScannerFragment extends WifiDppQrCodeBaseFragment impl
     public void onAccessPointsChanged() {
         // Do nothing.
     }
+
+    @VisibleForTesting
+    protected boolean isDecodeTaskAlive() {
+        return mCamera != null && mCamera.isDecodeTaskAlive();
+    }
 }