Create new isNetworkSupported API

Useful for checking if on a wifi-only device.
Similar to asking for NetworkInfo for a network type and checking for
null, though here the intent is explicit.

bug:5087537
Change-Id: Ia3ddd09b6b735b8b3ceb7a347891e015fd96b218

core/java/android/net/ConnectivityManager.java

@@ -814,4 +814,22 @@ public class ConnectivityManager {
         } catch (RemoteException e) {
         }
     }
+
+    /**
+     * Returns true if the hardware supports the given network type
+     * else it returns false.  This doesn't indicate we have coverage
+     * or are authorized onto a network, just whether or not the
+     * hardware supports it.  For example a gsm phone without a sim
+     * should still return true for mobile data, but a wifi only tablet
+     * would return false.
+     * @param networkType The nework type we'd like to check
+     * @return true if supported, else false
+     * @hide
+     */
+    public boolean isNetworkSupported(int networkType) {
+        try {
+            return mService.isNetworkSupported(networkType);
+        } catch (RemoteException e) {}
+        return false;
+    }
 }

core/java/android/net/IConnectivityManager.aidl

@@ -43,6 +43,8 @@ interface IConnectivityManager
     NetworkInfo getNetworkInfo(int networkType);
     NetworkInfo[] getAllNetworkInfo();
 
+    boolean isNetworkSupported(int networkType);
+
     LinkProperties getActiveLinkProperties();
     LinkProperties getLinkProperties(int networkType);
 

services/java/com/android/server/ConnectivityService.java

@@ -703,6 +703,12 @@ public class ConnectivityService extends IConnectivityManager.Stub {
         return result.toArray(new NetworkInfo[result.size()]);
     }
 
+    @Override
+    public boolean isNetworkSupported(int networkType) {
+        enforceAccessPermission();
+        return (isNetworkTypeValid(networkType) && (mNetTrackers[networkType] != null));
+    }
+
     /**
      * Return LinkProperties for the active (i.e., connected) default
      * network interface.  It is assumed that at most one default network