Add visibility control to ADB QR code preference.

The preference should be hidden if isAdbWifiQrSupported() is false.

Bug: 150163684
Bug: 149843499

Test: make RunSettingsRoboTests ROBOTEST_FILTER=AdbQrCodePreferenceControllerTest
Change-Id: I3e833440fb1a6f369ac97cec8db04f2b99dd4640
(cherry picked from commit 6178918653)
Exempt-From-Owner-Approval: cherry-pick

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

@@ -193,6 +193,7 @@ public class AdbQrcodeScannerFragment extends WifiDppQrCodeBaseFragment implemen
         } catch (RemoteException e) {
             Log.e(TAG, "Unable to cancel pairing");
         }
+        getActivity().setResult(Activity.RESULT_CANCELED);
         getActivity().finish();
     }
 
@@ -268,6 +269,7 @@ public class AdbQrcodeScannerFragment extends WifiDppQrCodeBaseFragment implemen
                     mAdbConfig.getPreSharedKey());
         } catch (RemoteException e) {
             Log.e(TAG, "Unable to enable QR code pairing");
+            getActivity().setResult(Activity.RESULT_CANCELED);
             getActivity().finish();
         }
     }