diff --git a/demos/main/src/main/java/com/google/android/exoplayer2/demo/DownloadTracker.java b/demos/main/src/main/java/com/google/android/exoplayer2/demo/DownloadTracker.java
index 8109263e55..b448dd40de 100644
--- a/demos/main/src/main/java/com/google/android/exoplayer2/demo/DownloadTracker.java
+++ b/demos/main/src/main/java/com/google/android/exoplayer2/demo/DownloadTracker.java
@@ -16,10 +16,12 @@
 package com.google.android.exoplayer2.demo;
 
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull;
 
 import android.content.Context;
 import android.content.DialogInterface;
 import android.net.Uri;
+import android.os.AsyncTask;
 import android.widget.Toast;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -170,6 +172,7 @@ public class DownloadTracker {
 
     private TrackSelectionDialog trackSelectionDialog;
     private MappedTrackInfo mappedTrackInfo;
+    private WidevineOfflineLicenseFetchTask widevineOfflineLicenseFetchTask;
     @Nullable private byte[] keySetId;
 
     public StartDownloadDialogHelper(
@@ -185,6 +188,9 @@ public class DownloadTracker {
       if (trackSelectionDialog != null) {
         trackSelectionDialog.dismiss();
       }
+      if (widevineOfflineLicenseFetchTask != null) {
+        widevineOfflineLicenseFetchTask.cancel(false);
+      }
     }
 
     // DownloadHelper.Callback implementation.
@@ -192,59 +198,32 @@ public class DownloadTracker {
     @Override
     public void onPrepared(@NonNull DownloadHelper helper) {
       @Nullable Format format = getFirstFormatWithDrmInitData(helper);
-      if (format != null) {
-        if (Util.SDK_INT < 18) {
-          Toast.makeText(context, R.string.error_drm_unsupported_before_api_18, Toast.LENGTH_LONG)
-              .show();
-          Log.e(TAG, "Downloading DRM protected content is not supported on API versions below 18");
-          return;
-        }
-        // TODO(internal b/163107948): Support cases where DrmInitData are not in the manifest.
-        if (!hasSchemaData(format.drmInitData)) {
-          Toast.makeText(context, R.string.download_start_error_offline_license, Toast.LENGTH_LONG)
-              .show();
-          Log.e(
-              TAG,
-              "Downloading content where DRM scheme data is not located in the manifest is not"
-                  + " supported");
-          return;
-        }
-        try {
-          // TODO(internal b/163107948): Download the license on another thread to keep the UI
-          //  thread unblocked.
-          fetchOfflineLicense(format);
-        } catch (DrmSession.DrmSessionException e) {
-          Toast.makeText(context, R.string.download_start_error_offline_license, Toast.LENGTH_LONG)
-              .show();
-          Log.e(TAG, "Failed to fetch offline DRM license", e);
-          return;
-        }
-      }
-
-      if (helper.getPeriodCount() == 0) {
-        Log.d(TAG, "No periods found. Downloading entire stream.");
-        startDownload();
-        downloadHelper.release();
+      if (format == null) {
+        onDownloadPrepared(helper);
         return;
       }
 
-      mappedTrackInfo = downloadHelper.getMappedTrackInfo(/* periodIndex= */ 0);
-      if (!TrackSelectionDialog.willHaveContent(mappedTrackInfo)) {
-        Log.d(TAG, "No dialog content. Downloading entire stream.");
-        startDownload();
-        downloadHelper.release();
+      // The content is DRM protected. We need to acquire an offline license.
+      if (Util.SDK_INT < 18) {
+        Toast.makeText(context, R.string.error_drm_unsupported_before_api_18, Toast.LENGTH_LONG)
+            .show();
+        Log.e(TAG, "Downloading DRM protected content is not supported on API versions below 18");
         return;
       }
-      trackSelectionDialog =
-          TrackSelectionDialog.createForMappedTrackInfoAndParameters(
-              /* titleId= */ R.string.exo_download_description,
-              mappedTrackInfo,
-              trackSelectorParameters,
-              /* allowAdaptiveSelections =*/ false,
-              /* allowMultipleOverrides= */ true,
-              /* onClickListener= */ this,
-              /* onDismissListener= */ this);
-      trackSelectionDialog.show(fragmentManager, /* tag= */ null);
+      // TODO(internal b/163107948): Support cases where DrmInitData are not in the manifest.
+      if (!hasSchemaData(format.drmInitData)) {
+        Toast.makeText(context, R.string.download_start_error_offline_license, Toast.LENGTH_LONG)
+            .show();
+        Log.e(
+            TAG,
+            "Downloading content where DRM scheme data is not located in the manifest is not"
+                + " supported");
+        return;
+      }
+      widevineOfflineLicenseFetchTask =
+          new WidevineOfflineLicenseFetchTask(
+              format, mediaItem.playbackProperties.drmConfiguration.licenseUri, this, helper);
+      widevineOfflineLicenseFetchTask.execute();
     }
 
     @Override
@@ -292,6 +271,44 @@ public class DownloadTracker {
 
     // Internal methods.
 
+    private void onOfflineLicenseFetched(DownloadHelper helper, byte[] keySetId) {
+      this.keySetId = keySetId;
+      onDownloadPrepared(helper);
+    }
+
+    private void onOfflineLicenseFetchedError(DrmSession.DrmSessionException e) {
+      Toast.makeText(context, R.string.download_start_error_offline_license, Toast.LENGTH_LONG)
+          .show();
+      Log.e(TAG, "Failed to fetch offline DRM license", e);
+    }
+
+    private void onDownloadPrepared(DownloadHelper helper) {
+      if (helper.getPeriodCount() == 0) {
+        Log.d(TAG, "No periods found. Downloading entire stream.");
+        startDownload();
+        downloadHelper.release();
+        return;
+      }
+
+      mappedTrackInfo = downloadHelper.getMappedTrackInfo(/* periodIndex= */ 0);
+      if (!TrackSelectionDialog.willHaveContent(mappedTrackInfo)) {
+        Log.d(TAG, "No dialog content. Downloading entire stream.");
+        startDownload();
+        downloadHelper.release();
+        return;
+      }
+      trackSelectionDialog =
+          TrackSelectionDialog.createForMappedTrackInfoAndParameters(
+              /* titleId= */ R.string.exo_download_description,
+              mappedTrackInfo,
+              trackSelectorParameters,
+              /* allowAdaptiveSelections =*/ false,
+              /* allowMultipleOverrides= */ true,
+              /* onClickListener= */ this,
+              /* onDismissListener= */ this);
+      trackSelectionDialog.show(fragmentManager, /* tag= */ null);
+    }
+
     private void startDownload() {
       startDownload(buildDownloadRequest());
     }
@@ -306,15 +323,54 @@ public class DownloadTracker {
           .getDownloadRequest(Util.getUtf8Bytes(checkNotNull(mediaItem.mediaMetadata.title)))
           .copyWithKeySetId(keySetId);
     }
+  }
 
-    @RequiresApi(18)
-    private void fetchOfflineLicense(Format format) throws DrmSession.DrmSessionException {
+  /** Downloads a Widevine offline license in a background thread. */
+  @RequiresApi(18)
+  private final class WidevineOfflineLicenseFetchTask extends AsyncTask<Void, Void, Void> {
+    private final Format format;
+    private final Uri licenseUri;
+    private final StartDownloadDialogHelper dialogHelper;
+    private final DownloadHelper downloadHelper;
+
+    @Nullable private byte[] keySetId;
+    @Nullable private DrmSession.DrmSessionException drmSessionException;
+
+    public WidevineOfflineLicenseFetchTask(
+        Format format,
+        Uri licenseUri,
+        StartDownloadDialogHelper dialogHelper,
+        DownloadHelper downloadHelper) {
+      this.format = format;
+      this.licenseUri = licenseUri;
+      this.dialogHelper = dialogHelper;
+      this.downloadHelper = downloadHelper;
+    }
+
+    @Override
+    protected Void doInBackground(Void... voids) {
       OfflineLicenseHelper offlineLicenseHelper =
           OfflineLicenseHelper.newWidevineInstance(
-              mediaItem.playbackProperties.drmConfiguration.licenseUri.toString(),
+              licenseUri.toString(),
               httpDataSourceFactory,
               new DrmSessionEventListener.EventDispatcher());
-      keySetId = offlineLicenseHelper.downloadLicense(format);
+      try {
+        keySetId = offlineLicenseHelper.downloadLicense(format);
+      } catch (DrmSession.DrmSessionException e) {
+        drmSessionException = e;
+      } finally {
+        offlineLicenseHelper.release();
+      }
+      return null;
+    }
+
+    @Override
+    protected void onPostExecute(Void aVoid) {
+      if (drmSessionException != null) {
+        dialogHelper.onOfflineLicenseFetchedError(drmSessionException);
+      } else {
+        dialogHelper.onOfflineLicenseFetched(downloadHelper, checkStateNotNull(keySetId));
+      }
     }
   }