API to report if active network is metered.

Report to developers if active network is "metered" and define it
as the user being sensitive to heavy data usage.

Bug: 3001465
Change-Id: I855ca3cd3eb1de3c4814148d70ccf24957af898a

core/java/android/net/ConnectivityManager.java

@@ -373,10 +373,11 @@ public class ConnectivityManager {
     }
 
     /**
-     * Gets you info about the current data network.
-     * Call {@link NetworkInfo#isConnected()} on the returned {@link NetworkInfo}
-     * to check if the device has a data connection.
-    */
+     * Returns details about the currently active data network. When connected,
+     * this network is the default route for outgoing connections. You should
+     * always check {@link NetworkInfo#isConnected()} before initiating network
+     * traffic. This may return {@code null} when no networks are available.
+     */
     public NetworkInfo getActiveNetworkInfo() {
         try {
             return mService.getActiveNetworkInfo();
@@ -856,4 +857,19 @@ public class ConnectivityManager {
         } catch (RemoteException e) {}
         return false;
     }
+
+    /**
+     * Returns if the currently active data network is metered. A network is
+     * classified as metered when the user is sensitive to heavy data usage on
+     * that connection. You should check this before doing large data transfers,
+     * and warn the user or delay the operation until another network is
+     * available.
+     */
+    public boolean isActiveNetworkMetered() {
+        try {
+            return mService.isActiveNetworkMetered();
+        } catch (RemoteException e) {
+            return false;
+        }
+    }
 }

core/java/android/net/IConnectivityManager.aidl

@@ -51,6 +51,7 @@ interface IConnectivityManager
     NetworkState[] getAllNetworkState();
 
     NetworkQuotaInfo getActiveNetworkQuotaInfo();
+    boolean isActiveNetworkMetered();
 
     boolean setRadios(boolean onOff);
 

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

@@ -875,6 +875,19 @@ private NetworkStateTracker makeWimaxStateTracker() {
         return null;
     }
 
+    @Override
+    public boolean isActiveNetworkMetered() {
+        enforceAccessPermission();
+        final NetworkState state = getNetworkStateUnchecked(mActiveDefaultNetwork);
+        if (state != null) {
+            try {
+                return mPolicyManager.isNetworkMetered(state);
+            } catch (RemoteException e) {
+            }
+        }
+        return false;
+    }
+
     public boolean setRadios(boolean turnOn) {
         boolean result = true;
         enforceChangePermission();