diff --git a/core/java/android/app/usage/NetworkStats.java b/core/java/android/app/usage/NetworkStats.java
index 2e44a630b0..da36157d85 100644
--- a/core/java/android/app/usage/NetworkStats.java
+++ b/core/java/android/app/usage/NetworkStats.java
@@ -227,6 +227,30 @@ public final class NetworkStats implements AutoCloseable {
          */
         public static final int ROAMING_YES = 0x2;
 
+        /** @hide */
+        @IntDef(prefix = { "DEFAULT_NETWORK_" }, value = {
+                DEFAULT_NETWORK_ALL,
+                DEFAULT_NETWORK_NO,
+                DEFAULT_NETWORK_YES
+        })
+        @Retention(RetentionPolicy.SOURCE)
+        public @interface DefaultNetwork {}
+
+        /**
+         * Combined usage for this network regardless of whether it was the active default network.
+         */
+        public static final int DEFAULT_NETWORK_ALL = -1;
+
+        /**
+         * Usage that occurs while this network is not the active default network.
+         */
+        public static final int DEFAULT_NETWORK_NO = 0x1;
+
+        /**
+         * Usage that occurs while this network is the active default network.
+         */
+        public static final int DEFAULT_NETWORK_YES = 0x2;
+
         /**
          * Special TAG value for total data across all tags
          */
@@ -235,6 +259,7 @@ public final class NetworkStats implements AutoCloseable {
         private int mUid;
         private int mTag;
         private int mState;
+        private int mDefaultNetwork;
         private int mMetered;
         private int mRoaming;
         private long mBeginTimeStamp;
@@ -286,6 +311,15 @@ public final class NetworkStats implements AutoCloseable {
             return 0;
         }
 
+        private static @DefaultNetwork int convertDefaultNetwork(int defaultNetwork) {
+            switch (defaultNetwork) {
+                case android.net.NetworkStats.DEFAULT_NETWORK_ALL : return DEFAULT_NETWORK_ALL;
+                case android.net.NetworkStats.DEFAULT_NETWORK_NO: return DEFAULT_NETWORK_NO;
+                case android.net.NetworkStats.DEFAULT_NETWORK_YES: return DEFAULT_NETWORK_YES;
+            }
+            return 0;
+        }
+
         public Bucket() {
         }
 
@@ -350,6 +384,21 @@ public final class NetworkStats implements AutoCloseable {
             return mRoaming;
         }
 
+        /**
+         * Default network state. One of the following values:<p/>
+         * <ul>
+         * <li>{@link #DEFAULT_NETWORK_ALL}</li>
+         * <li>{@link #DEFAULT_NETWORK_NO}</li>
+         * <li>{@link #DEFAULT_NETWORK_YES}</li>
+         * </ul>
+         * <p>Indicates whether the network usage occurred on the system default network for this
+         * type of traffic, or whether the application chose to send this traffic on a network that
+         * was not the one selected by the system.
+         */
+        public @DefaultNetwork int getDefaultNetwork() {
+            return mDefaultNetwork;
+        }
+
         /**
          * Start timestamp of the bucket's time interval. Defined in terms of "Unix time", see
          * {@link java.lang.System#currentTimeMillis}.
@@ -551,6 +600,8 @@ public final class NetworkStats implements AutoCloseable {
         bucketOut.mUid = Bucket.convertUid(mRecycledSummaryEntry.uid);
         bucketOut.mTag = Bucket.convertTag(mRecycledSummaryEntry.tag);
         bucketOut.mState = Bucket.convertState(mRecycledSummaryEntry.set);
+        bucketOut.mDefaultNetwork = Bucket.convertDefaultNetwork(
+                mRecycledSummaryEntry.defaultNetwork);
         bucketOut.mMetered = Bucket.convertMetered(mRecycledSummaryEntry.metered);
         bucketOut.mRoaming = Bucket.convertRoaming(mRecycledSummaryEntry.roaming);
         bucketOut.mBeginTimeStamp = mStartTimeStamp;
@@ -600,6 +651,7 @@ public final class NetworkStats implements AutoCloseable {
                 bucketOut.mUid = Bucket.convertUid(getUid());
                 bucketOut.mTag = Bucket.convertTag(mTag);
                 bucketOut.mState = Bucket.STATE_ALL;
+                bucketOut.mDefaultNetwork = Bucket.DEFAULT_NETWORK_ALL;
                 bucketOut.mMetered = Bucket.METERED_ALL;
                 bucketOut.mRoaming = Bucket.ROAMING_ALL;
                 bucketOut.mBeginTimeStamp = mRecycledHistoryEntry.bucketStart;
diff --git a/core/java/android/app/usage/NetworkStatsManager.java b/core/java/android/app/usage/NetworkStatsManager.java
index 853b00331a..90b514e272 100644
--- a/core/java/android/app/usage/NetworkStatsManager.java
+++ b/core/java/android/app/usage/NetworkStatsManager.java
@@ -60,10 +60,11 @@ import android.util.Log;
  * {@link #queryDetailsForUid} <p />
  * {@link #queryDetails} <p />
  * These queries do not aggregate over time but do aggregate over state, metered and roaming.
- * Therefore there can be multiple buckets for a particular key but all Bucket's state is going to
- * be {@link NetworkStats.Bucket#STATE_ALL}, all Bucket's metered is going to be
- * {@link NetworkStats.Bucket#METERED_ALL}, and all Bucket's roaming is going to be
- * {@link NetworkStats.Bucket#ROAMING_ALL}.
+ * Therefore there can be multiple buckets for a particular key. However, all Buckets will have
+ * {@code state} {@link NetworkStats.Bucket#STATE_ALL},
+ * {@code defaultNetwork} {@link NetworkStats.Bucket#DEFAULT_NETWORK_ALL},
+ * {@code metered } {@link NetworkStats.Bucket#METERED_ALL},
+ * {@code roaming} {@link NetworkStats.Bucket#ROAMING_ALL}.
  * <p />
  * <b>NOTE:</b> Calling {@link #querySummaryForDevice} or accessing stats for apps other than the
  * calling app requires the permission {@link android.Manifest.permission#PACKAGE_USAGE_STATS},
@@ -136,7 +137,9 @@ public class NetworkStatsManager {
      * roaming. This means the bucket's start and end timestamp are going to be the same as the
      * 'startTime' and 'endTime' parameters. State is going to be
      * {@link NetworkStats.Bucket#STATE_ALL}, uid {@link NetworkStats.Bucket#UID_ALL},
-     * tag {@link NetworkStats.Bucket#TAG_NONE}, metered {@link NetworkStats.Bucket#METERED_ALL},
+     * tag {@link NetworkStats.Bucket#TAG_NONE},
+     * default network {@link NetworkStats.Bucket#DEFAULT_NETWORK_ALL},
+     * metered {@link NetworkStats.Bucket#METERED_ALL},
      * and roaming {@link NetworkStats.Bucket#ROAMING_ALL}.
      *
      * @param networkType As defined in {@link ConnectivityManager}, e.g.
@@ -209,10 +212,10 @@ public class NetworkStatsManager {
     /**
      * Query network usage statistics summaries. Result filtered to include only uids belonging to
      * calling user. Result is aggregated over time, hence all buckets will have the same start and
-     * end timestamps. Not aggregated over state, uid, metered, or roaming. This means buckets'
-     * start and end timestamps are going to be the same as the 'startTime' and 'endTime'
-     * parameters. State, uid, metered, and roaming are going to vary, and tag is going to be the
-     * same.
+     * end timestamps. Not aggregated over state, uid, default network, metered, or roaming. This
+     * means buckets' start and end timestamps are going to be the same as the 'startTime' and
+     * 'endTime' parameters. State, uid, metered, and roaming are going to vary, and tag is going to
+     * be the same.
      *
      * @param networkType As defined in {@link ConnectivityManager}, e.g.
      *            {@link ConnectivityManager#TYPE_MOBILE}, {@link ConnectivityManager#TYPE_WIFI}
@@ -258,9 +261,10 @@ public class NetworkStatsManager {
      * belonging to calling user. Result is aggregated over state but not aggregated over time.
      * This means buckets' start and end timestamps are going to be between 'startTime' and
      * 'endTime' parameters. State is going to be {@link NetworkStats.Bucket#STATE_ALL}, uid the
-     * same as the 'uid' parameter and tag the same as 'tag' parameter. metered is going to be
-     * {@link NetworkStats.Bucket#METERED_ALL}, and roaming is going to be
-     * {@link NetworkStats.Bucket#ROAMING_ALL}.
+     * same as the 'uid' parameter and tag the same as 'tag' parameter.
+     * defaultNetwork is going to be {@link NetworkStats.Bucket#DEFAULT_NETWORK_ALL},
+     * metered is going to be {@link NetworkStats.Bucket#METERED_ALL}, and
+     * roaming is going to be {@link NetworkStats.Bucket#ROAMING_ALL}.
      * <p>Only includes buckets that atomically occur in the inclusive time range. Doesn't
      * interpolate across partial buckets. Since bucket length is in the order of hours, this
      * method cannot be used to measure data usage on a fine grained time scale.
@@ -301,9 +305,10 @@ public class NetworkStatsManager {
      * metered, nor roaming. This means buckets' start and end timestamps are going to be between
      * 'startTime' and 'endTime' parameters. State is going to be
      * {@link NetworkStats.Bucket#STATE_ALL}, uid will vary,
-     * tag {@link NetworkStats.Bucket#TAG_NONE}, metered is going to be
-     * {@link NetworkStats.Bucket#METERED_ALL}, and roaming is going to be
-     * {@link NetworkStats.Bucket#ROAMING_ALL}.
+     * tag {@link NetworkStats.Bucket#TAG_NONE},
+     * default network is going to be {@link NetworkStats.Bucket#DEFAULT_NETWORK_ALL},
+     * metered is going to be {@link NetworkStats.Bucket#METERED_ALL},
+     * and roaming is going to be {@link NetworkStats.Bucket#ROAMING_ALL}.
      * <p>Only includes buckets that atomically occur in the inclusive time range. Doesn't
      * interpolate across partial buckets. Since bucket length is in the order of hours, this
      * method cannot be used to measure data usage on a fine grained time scale.
diff --git a/core/java/android/net/NetworkIdentity.java b/core/java/android/net/NetworkIdentity.java
index fd118f3401..ce2de8554d 100644
--- a/core/java/android/net/NetworkIdentity.java
+++ b/core/java/android/net/NetworkIdentity.java
@@ -130,6 +130,7 @@ public class NetworkIdentity implements Comparable<NetworkIdentity> {
         proto.write(NetworkIdentityProto.NETWORK_ID, mNetworkId);
         proto.write(NetworkIdentityProto.ROAMING, mRoaming);
         proto.write(NetworkIdentityProto.METERED, mMetered);
+        proto.write(NetworkIdentityProto.DEFAULT_NETWORK, mDefaultNetwork);
 
         proto.end(start);
     }