[a11y] Fix TalkBack readback on adb qrcode fragment.

TalkBack was picking up the text in the action bar, so if we hide it,
it will read the first body of text it encounters which would be "Scan
QR code. Pair device over Wi-Fi by scanning a QR code."

Bug: 152461605

Test: Manual. Enable TalkBack in Settings > Accessibility > TalkBack.
Navigate to Developer options > Wireless debugging > Pair by QR code.
When QR code scanner fragment opens, it should say "Scan QR code. Pair
device over Wi-Fi by scanning a QR code."

Change-Id: Ia91bf4ea215e6a377335f2b9dcf2acf10afd268e

src/com/android/settings/development/AdbQrcodeScannerFragment.java

@@ -207,6 +207,15 @@ public class AdbQrcodeScannerFragment extends WifiDppQrCodeBaseFragment implemen
         super.onAttach(context);
     }
 
+    @Override
+    public void onActivityCreated(Bundle savedInstanceState) {
+        super.onActivityCreated(savedInstanceState);
+
+        getActivity().getActionBar().hide();
+        // setTitle for TalkBack
+        getActivity().setTitle(R.string.wifi_dpp_scan_qr_code);
+    }
+
     @Override
     public int getMetricsCategory() {
         return 0;