Fix the Wi-Fi detailed settings un-editable issue.

- The WifiEntry info might not be ready in early stage. (ex:
WifiEntry#canSetPrivacy())

- The Wi-Fi detailed setting listens to the WifiEntry callback to
refresh the preferences, it should first update the preference status to
be editable or not, and then display preferences to the UI.

- The privicy preference should be able to set back to selectable when
WifiEntry#canSetPrivicy() change from false to true.

Bug: 170148009
Test:
make RunSettingsRoboTests
ROBOTEST_FILTER=WifiNetworkDetailsFragment2Test
make RunSettingsRoboTests
ROBOTEST_FILTER=WifiPrivacyPreferenceController2Test

Change-Id: I48ca060e6b468232f19c82e9de0ce4fce39cba7f
Merged-In: I567b2b80163631a01d165c0ac5c0aba392e014ef

src/com/android/settings/wifi/details2/WifiPrivacyPreferenceController2.java

@@ -69,12 +69,13 @@ public class WifiPrivacyPreferenceController2 extends BasePreferenceController i
     public void updateState(Preference preference) {
         final DropDownPreference dropDownPreference = (DropDownPreference) preference;
         final int randomizationLevel = getRandomizationValue();
+        final boolean isSelectable = mWifiEntry.canSetPrivacy();
+        preference.setSelectable(isSelectable);
         dropDownPreference.setValue(Integer.toString(randomizationLevel));
         updateSummary(dropDownPreference, randomizationLevel);
 
-        // Makes preference not selectable, when this is a ephemeral network.
-        if (!mWifiEntry.canSetPrivacy()) {
-            preference.setSelectable(false);
+        // If the preference cannot be selectable, display a temporary network in the summary.
+        if (!isSelectable) {
             dropDownPreference.setSummary(R.string.wifi_privacy_settings_ephemeral_summary);
         }
     }