Expose getTx/RxBytes in TrafficStats

Test: atest FrameworksNetTests TrafficStatsTest
      atest android.net.cts android.net.wifi.cts
Bug: 164965653
Change-Id: I17b9d0bc2404c5727d4c4530ad941439b7b71a54

core/java/android/net/TrafficStats.java

@@ -597,10 +597,17 @@ public class TrafficStats {
     }
 
     /**
-     * Return the number of packets transmitted on the specified interface since
+     * Return the number of packets transmitted on the specified interface since the interface
-     * device boot. Statistics are measured at the network layer, so both TCP and
+     * was created. Statistics are measured at the network layer, so both TCP and
      * UDP usage are included.
      *
+     * Note that the returned values are partial statistics that do not count data from several
+     * sources and do not apply several adjustments that are necessary for correctness, such
+     * as adjusting for VPN apps, IPv6-in-IPv4 translation, etc. These values can be used to
+     * determine whether traffic is being transferred on the specific interface but are not a
+     * substitute for the more accurate statistics provided by the {@link NetworkStatsManager}
+     * APIs.
+     *
      * @param iface The name of the interface.
      * @return The number of transmitted packets.
      */
@@ -613,10 +620,17 @@ public class TrafficStats {
     }
 
     /**
-     * Return the number of packets received on the specified interface since
+     * Return the number of packets received on the specified interface since the interface was
-     * device boot. Statistics are measured at the network layer, so both TCP
+     * created. Statistics are measured at the network layer, so both TCP
      * and UDP usage are included.
      *
+     * Note that the returned values are partial statistics that do not count data from several
+     * sources and do not apply several adjustments that are necessary for correctness, such
+     * as adjusting for VPN apps, IPv6-in-IPv4 translation, etc. These values can be used to
+     * determine whether traffic is being transferred on the specific interface but are not a
+     * substitute for the more accurate statistics provided by the {@link NetworkStatsManager}
+     * APIs.
+     *
      * @param iface The name of the interface.
      * @return The number of received packets.
      */
@@ -628,9 +642,22 @@ public class TrafficStats {
         }
     }
 
-    /** {@hide} */
+    /**
-    @UnsupportedAppUsage
+     * Return the number of bytes transmitted on the specified interface since the interface
-    public static long getTxBytes(String iface) {
+     * was created. Statistics are measured at the network layer, so both TCP and
+     * UDP usage are included.
+     *
+     * Note that the returned values are partial statistics that do not count data from several
+     * sources and do not apply several adjustments that are necessary for correctness, such
+     * as adjusting for VPN apps, IPv6-in-IPv4 translation, etc. These values can be used to
+     * determine whether traffic is being transferred on the specific interface but are not a
+     * substitute for the more accurate statistics provided by the {@link NetworkStatsManager}
+     * APIs.
+     *
+     * @param iface The name of the interface.
+     * @return The number of transmitted bytes.
+     */
+    public static long getTxBytes(@NonNull String iface) {
         try {
             return getStatsService().getIfaceStats(iface, TYPE_TX_BYTES);
         } catch (RemoteException e) {
@@ -638,9 +665,22 @@ public class TrafficStats {
         }
     }
 
-    /** {@hide} */
+    /**
-    @UnsupportedAppUsage
+     * Return the number of bytes received on the specified interface since the interface
-    public static long getRxBytes(String iface) {
+     * was created. Statistics are measured at the network layer, so both TCP
+     * and UDP usage are included.
+     *
+     * Note that the returned values are partial statistics that do not count data from several
+     * sources and do not apply several adjustments that are necessary for correctness, such
+     * as adjusting for VPN apps, IPv6-in-IPv4 translation, etc. These values can be used to
+     * determine whether traffic is being transferred on the specific interface but are not a
+     * substitute for the more accurate statistics provided by the {@link NetworkStatsManager}
+     * APIs.
+     *
+     * @param iface The name of the interface.
+     * @return The number of received bytes.
+     */
+    public static long getRxBytes(@NonNull String iface) {
         try {
             return getStatsService().getIfaceStats(iface, TYPE_RX_BYTES);
         } catch (RemoteException e) {