Refer to the last Hotspot password when generating the password

- Query the last Hotspot password when security type is SECURITY_TYPE_OPEN and it will be used when the user changes to another security type

- If the last hotspot password is an empty string, then generate random password

Bug: 201789473
Test: manual test
atest -c WifiHotspotRepositoryTest
make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherPasswordPreferenceControllerTest

Change-Id: Id3a846099238433e7b6c8b934fa26a74df0dcb61

src/com/android/settings/overlay/FeatureFactoryImpl.java

@@ -77,6 +77,7 @@ import com.android.settings.vpn2.AdvancedVpnFeatureProvider;
 import com.android.settings.vpn2.AdvancedVpnFeatureProviderImpl;
 import com.android.settings.wifi.WifiTrackerLibProvider;
 import com.android.settings.wifi.WifiTrackerLibProviderImpl;
+import com.android.settings.wifi.factory.WifiFeatureProvider;
 import com.android.settingslib.core.instrumentation.MetricsFeatureProvider;
 
 /**
@@ -112,6 +113,7 @@ public class FeatureFactoryImpl extends FeatureFactory {
     private AccessibilitySearchFeatureProvider mAccessibilitySearchFeatureProvider;
     private AccessibilityMetricsFeatureProvider mAccessibilityMetricsFeatureProvider;
     private AdvancedVpnFeatureProvider mAdvancedVpnFeatureProvider;
+    private WifiFeatureProvider mWifiFeatureProvider;
 
     @Override
     public SupportFeatureProvider getSupportFeatureProvider(Context context) {
@@ -355,4 +357,12 @@ public class FeatureFactoryImpl extends FeatureFactory {
         }
         return mAdvancedVpnFeatureProvider;
     }
+
+    @Override
+    public WifiFeatureProvider getWifiFeatureProvider() {
+        if (mWifiFeatureProvider == null) {
+            mWifiFeatureProvider = new WifiFeatureProvider(getAppContext());
+        }
+        return mWifiFeatureProvider;
+    }
 }