diff --git a/library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadIndexUtil.java b/library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadIndexUtil.java
new file mode 100644
index 0000000000..63602c7641
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadIndexUtil.java
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.offline;
+
+import android.support.annotation.Nullable;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.offline.DownloadState.State;
+import com.google.android.exoplayer2.util.Assertions;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashSet;
+
+/** {@link DownloadIndex} related utility methods. */
+public final class DownloadIndexUtil {
+
+  /** An interface to provide custom download ids during ActionFile upgrade. */
+  public interface DownloadIdProvider {
+
+    /**
+     * Returns a custom download id for given action.
+     *
+     * @param downloadAction The action which is an id requested for.
+     * @return A custom download id for given action.
+     */
+    String getId(DownloadAction downloadAction);
+  }
+
+  private DownloadIndexUtil() {}
+
+  /**
+   * Upgrades an {@link ActionFile} to {@link DownloadIndex}.
+   *
+   * <p>This method shouldn't be called while {@link DownloadIndex} is used by {@link
+   * DownloadManager}.
+   *
+   * @param actionFile The action file to upgrade.
+   * @param downloadIndex Actions are converted to {@link DownloadState}s and stored in this index.
+   * @param downloadIdProvider A nullable custom download id provider.
+   * @throws IOException If there is an error during loading actions.
+   */
+  public static void upgradeActionFile(
+      ActionFile actionFile,
+      DownloadIndex downloadIndex,
+      @Nullable DownloadIdProvider downloadIdProvider)
+      throws IOException {
+    if (downloadIdProvider == null) {
+      downloadIdProvider = downloadAction -> downloadAction.id;
+    }
+    for (DownloadAction action : actionFile.load()) {
+      addAction(downloadIndex, downloadIdProvider.getId(action), action);
+    }
+  }
+
+  /**
+   * Converts a {@link DownloadAction} to {@link DownloadState} and stored in the given {@link
+   * DownloadIndex}.
+   *
+   * <p>This method shouldn't be called while {@link DownloadIndex} is used by {@link
+   * DownloadManager}.
+   *
+   * @param downloadIndex The action is converted to {@link DownloadState} and stored in this index.
+   * @param id A nullable custom download id which overwrites {@link DownloadAction#id}.
+   * @param action The action to be stored in {@link DownloadIndex}.
+   */
+  public static void addAction(
+      DownloadIndex downloadIndex, @Nullable String id, DownloadAction action) {
+    DownloadState downloadState = downloadIndex.getDownloadState(id != null ? id : action.id);
+    if (downloadState != null) {
+      downloadState = merge(downloadState, action);
+    } else {
+      downloadState = convert(action);
+    }
+    downloadIndex.putDownloadState(downloadState);
+  }
+
+  private static DownloadState merge(DownloadState downloadState, DownloadAction action) {
+    Assertions.checkArgument(action.type.equals(downloadState.type));
+    @State int newState;
+    if (action.isRemoveAction) {
+      newState = DownloadState.STATE_REMOVING;
+    } else {
+      if (downloadState.state == DownloadState.STATE_REMOVING
+          || downloadState.state == DownloadState.STATE_RESTARTING) {
+        newState = DownloadState.STATE_RESTARTING;
+      } else if (downloadState.state == DownloadState.STATE_STOPPED) {
+        newState = DownloadState.STATE_STOPPED;
+      } else {
+        newState = DownloadState.STATE_QUEUED;
+      }
+    }
+    HashSet<StreamKey> keys = new HashSet<>(action.keys);
+    Collections.addAll(keys, downloadState.streamKeys);
+    StreamKey[] newKeys = keys.toArray(new StreamKey[0]);
+    return new DownloadState(
+        downloadState.id,
+        downloadState.type,
+        action.uri,
+        action.customCacheKey,
+        newState,
+        /* downloadPercentage= */ C.PERCENTAGE_UNSET,
+        downloadState.downloadedBytes,
+        /* totalBytes= */ C.LENGTH_UNSET,
+        downloadState.failureReason,
+        downloadState.stopFlags,
+        downloadState.startTimeMs,
+        downloadState.updateTimeMs,
+        newKeys,
+        action.data);
+  }
+
+  private static DownloadState convert(DownloadAction action) {
+    long currentTimeMs = System.currentTimeMillis();
+    return new DownloadState(
+        action.id,
+        action.type,
+        action.uri,
+        action.customCacheKey,
+        /* state= */ action.isRemoveAction
+            ? DownloadState.STATE_REMOVING
+            : DownloadState.STATE_QUEUED,
+        /* downloadPercentage= */ C.PERCENTAGE_UNSET,
+        /* downloadedBytes= */ 0,
+        /* totalBytes= */ C.LENGTH_UNSET,
+        DownloadState.FAILURE_REASON_NONE,
+        /* stopFlags= */ 0,
+        /* startTimeMs= */ currentTimeMs,
+        /* updateTimeMs= */ currentTimeMs,
+        action.keys.toArray(new StreamKey[0]),
+        action.data);
+  }
+}
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadIndexUtilTest.java b/library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadIndexUtilTest.java
new file mode 100644
index 0000000000..376c840296
--- /dev/null
+++ b/library/core/src/test/java/com/google/android/exoplayer2/offline/DownloadIndexUtilTest.java
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.offline;
+
+import static com.google.android.exoplayer2.offline.DownloadAction.TYPE_DASH;
+import static com.google.common.truth.Truth.assertThat;
+
+import android.net.Uri;
+import com.google.android.exoplayer2.util.Util;
+import java.io.File;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+/** Unit tests for {@link DownloadIndexUtil}. */
+@RunWith(RobolectricTestRunner.class)
+public class DownloadIndexUtilTest {
+
+  private DefaultDownloadIndex downloadIndex;
+  private File tempFile;
+
+  @Before
+  public void setUp() throws Exception {
+    tempFile = Util.createTempFile(RuntimeEnvironment.application, "ExoPlayerTest");
+    downloadIndex = new DefaultDownloadIndex(RuntimeEnvironment.application);
+  }
+
+  @After
+  public void tearDown() {
+    downloadIndex.release();
+    tempFile.delete();
+  }
+
+  @Test
+  public void addAction_nonExistingDownloadState_createsNewDownloadState() {
+    byte[] data = new byte[] {1, 2, 3, 4};
+    DownloadAction action =
+        DownloadAction.createDownloadAction(
+            TYPE_DASH,
+            Uri.parse("https://www.test.com/download"),
+            asList(
+                new StreamKey(/* periodIndex= */ 0, /* groupIndex= */ 1, /* trackIndex= */ 2),
+                new StreamKey(/* periodIndex= */ 3, /* groupIndex= */ 4, /* trackIndex= */ 5)),
+            /* customCacheKey= */ "key123",
+            data);
+
+    DownloadIndexUtil.addAction(downloadIndex, action.id, action);
+
+    assertDownloadIndexContainsAction(action, DownloadState.STATE_QUEUED);
+  }
+
+  @Test
+  public void addAction_existingDownloadState_createsMergedDownloadState() {
+    StreamKey streamKey1 =
+        new StreamKey(/* periodIndex= */ 3, /* groupIndex= */ 4, /* trackIndex= */ 5);
+    StreamKey streamKey2 =
+        new StreamKey(/* periodIndex= */ 0, /* groupIndex= */ 1, /* trackIndex= */ 2);
+    DownloadAction action1 =
+        DownloadAction.createDownloadAction(
+            TYPE_DASH,
+            Uri.parse("https://www.test.com/download1"),
+            asList(streamKey1),
+            /* customCacheKey= */ "key123",
+            new byte[] {1, 2, 3, 4});
+    DownloadAction action2 =
+        DownloadAction.createDownloadAction(
+            TYPE_DASH,
+            Uri.parse("https://www.test.com/download2"),
+            asList(streamKey2),
+            /* customCacheKey= */ "key123",
+            new byte[] {5, 4, 3, 2, 1});
+    DownloadIndexUtil.addAction(downloadIndex, action1.id, action1);
+
+    DownloadIndexUtil.addAction(downloadIndex, action2.id, action2);
+
+    DownloadState downloadState = downloadIndex.getDownloadState(action2.id);
+    assertThat(downloadState).isNotNull();
+    assertThat(downloadState.type).isEqualTo(action2.type);
+    assertThat(downloadState.cacheKey).isEqualTo(action2.customCacheKey);
+    assertThat(downloadState.customMetadata).isEqualTo(action2.data);
+    assertThat(downloadState.uri).isEqualTo(action2.uri);
+    assertThat(downloadState.streamKeys).isEqualTo(new StreamKey[] {streamKey2, streamKey1});
+    assertThat(downloadState.state).isEqualTo(DownloadState.STATE_QUEUED);
+  }
+
+  @Test
+  public void upgradeActionFile_createsDownloadStates() throws Exception {
+    ActionFile actionFile = new ActionFile(tempFile);
+    StreamKey streamKey1 =
+        new StreamKey(/* periodIndex= */ 3, /* groupIndex= */ 4, /* trackIndex= */ 5);
+    StreamKey streamKey2 =
+        new StreamKey(/* periodIndex= */ 0, /* groupIndex= */ 1, /* trackIndex= */ 2);
+    DownloadAction action1 =
+        DownloadAction.createDownloadAction(
+            TYPE_DASH,
+            Uri.parse("https://www.test.com/download1"),
+            asList(streamKey1),
+            /* customCacheKey= */ "key123",
+            new byte[] {1, 2, 3, 4});
+    DownloadAction action2 =
+        DownloadAction.createDownloadAction(
+            TYPE_DASH,
+            Uri.parse("https://www.test.com/download2"),
+            asList(streamKey2),
+            /* customCacheKey= */ "key234",
+            new byte[] {5, 4, 3, 2, 1});
+    actionFile.store(action1, action2);
+    DownloadAction action3 =
+        DownloadAction.createRemoveAction(
+            TYPE_DASH, Uri.parse("https://www.test.com/download3"), /* customCacheKey= */ "key345");
+    actionFile.store(action1, action2, action3);
+
+    DownloadIndexUtil.upgradeActionFile(actionFile, downloadIndex, /* downloadIdProvider= */ null);
+
+    assertDownloadIndexContainsAction(action1, DownloadState.STATE_QUEUED);
+    assertDownloadIndexContainsAction(action2, DownloadState.STATE_QUEUED);
+    assertDownloadIndexContainsAction(action3, DownloadState.STATE_REMOVING);
+  }
+
+  private void assertDownloadIndexContainsAction(DownloadAction action, int state) {
+    DownloadState downloadState = downloadIndex.getDownloadState(action.id);
+    assertThat(downloadState).isNotNull();
+    assertThat(downloadState.type).isEqualTo(action.type);
+    assertThat(downloadState.cacheKey).isEqualTo(action.customCacheKey);
+    assertThat(downloadState.customMetadata).isEqualTo(action.data);
+    assertThat(downloadState.uri).isEqualTo(action.uri);
+    assertThat(downloadState.streamKeys).isEqualTo(action.keys.toArray(new StreamKey[0]));
+    assertThat(downloadState.state).isEqualTo(state);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static List<StreamKey> asList(StreamKey... streamKeys) {
+    return Arrays.asList(streamKeys);
+  }
+}