Surface metered networks as "Mobile hotspots."

String changes to give clearer definition of metered networks, and
remove metered control for mobile network.  Also fix NPE when testing
hasEthernet() before session is ready.

Bug: 6494976
Change-Id: Ia55ca3362a05977b9f21ab41eb10bbc738e29620

src/com/android/settings/net/DataUsageMeteredSettings.java

@@ -41,6 +41,8 @@ import com.android.settings.SettingsPreferenceFragment;
  */
 public class DataUsageMeteredSettings extends SettingsPreferenceFragment {
 
+    private static final boolean SHOW_MOBILE_CATEGORY = false;
+
     private NetworkPolicyManager mPolicyManager;
     private WifiManager mWifiManager;
 
@@ -70,7 +72,7 @@ public class DataUsageMeteredSettings extends SettingsPreferenceFragment {
     }
 
     private void updateNetworks(Context context) {
-        if (hasReadyMobileRadio(context)) {
+        if (SHOW_MOBILE_CATEGORY && hasReadyMobileRadio(context)) {
             mMobileCategory.removeAll();
             mMobileCategory.addPreference(buildMobilePref(context));
         } else {