Hide wifi card sometimes.

When there is a connected wifi, we now hide the wifi slice card.

However, if we initially shows this card but later wifi is connected
while the card is visible, we keep showing this card to avoid janky
animation. The card will be gone if user nagivates to a different UI and
comes back.

- Create a new slice ContextualWifiSlice for homepage use case, all
  special logic for homepage are added here.
- Change reference for WIFI_SLICE to CONTEXTUAL_WIFI_SLICE where make
  sense.

Change-Id: Ibd87f88058f357aabef0f7d68a5bf48350d75b06
Fixes: 121040746
Test: robotests

src/com/android/settings/wifi/WifiDialogActivity.java

@@ -38,6 +38,8 @@ public class WifiDialogActivity extends Activity implements WifiDialog.WifiDialo
 
     private static final String TAG = "WifiDialogActivity";
 
+    public static final String KEY_ACCESS_POINT_STATE = "access_point_state";
+
     /**
      * Boolean extra indicating whether this activity should connect to an access point on the
      * caller's behalf. If this is set to false, the caller should check
@@ -46,9 +48,8 @@ public class WifiDialogActivity extends Activity implements WifiDialog.WifiDialo
      */
     @VisibleForTesting
     static final String KEY_CONNECT_FOR_CALLER = "connect_for_caller";
-    static final String KEY_ACCESS_POINT_STATE = "access_point_state";
-    private static final String KEY_WIFI_CONFIGURATION = "wifi_configuration";
 
+    private static final String KEY_WIFI_CONFIGURATION = "wifi_configuration";
     private static final int RESULT_CONNECTED = RESULT_FIRST_USER;
     private static final int RESULT_FORGET = RESULT_FIRST_USER + 1;