Move DownloadManager initialization into the application

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=195317847

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoApplication.java

@@ -16,6 +16,13 @@
 package com.google.android.exoplayer2.demo;
 
 import android.app.Application;
+import com.google.android.exoplayer2.offline.DownloadAction.Deserializer;
+import com.google.android.exoplayer2.offline.DownloadManager;
+import com.google.android.exoplayer2.offline.DownloaderConstructorHelper;
+import com.google.android.exoplayer2.offline.ProgressiveDownloadAction;
+import com.google.android.exoplayer2.source.dash.offline.DashDownloadAction;
+import com.google.android.exoplayer2.source.hls.offline.HlsDownloadAction;
+import com.google.android.exoplayer2.source.smoothstreaming.offline.SsDownloadAction;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
@@ -37,10 +44,20 @@ public class DemoApplication extends Application {
 
   private static final String DOWNLOAD_ACTION_FILE = "actions";
   private static final String DOWNLOAD_CONTENT_DIRECTORY = "downloads";
+  private static final int MAX_SIMULTANEOUS_DOWNLOADS = 2;
+  private static final Deserializer[] DOWNLOAD_DESERIALIZERS =
+      new Deserializer[] {
+        DashDownloadAction.DESERIALIZER,
+        HlsDownloadAction.DESERIALIZER,
+        SsDownloadAction.DESERIALIZER,
+        ProgressiveDownloadAction.DESERIALIZER
+      };
 
   protected String userAgent;
+
   private File downloadDirectory;
   private Cache downloadCache;
+  private DownloadManager downloadManager;
 
   @Override
   public void onCreate() {
@@ -52,7 +69,7 @@ public class DemoApplication extends Application {
   public DataSource.Factory buildDataSourceFactory(TransferListener<? super DataSource> listener) {
     DefaultDataSourceFactory upstreamFactory =
         new DefaultDataSourceFactory(this, listener, buildHttpDataSourceFactory(listener));
-    return createReadOnlyCacheDataSource(upstreamFactory, getDownloadCache());
+    return buildReadOnlyCacheDataSource(upstreamFactory, getDownloadCache());
   }
 
   /** Returns a {@link HttpDataSource.Factory}. */
@@ -66,8 +83,23 @@ public class DemoApplication extends Application {
     return "withExtensions".equals(BuildConfig.FLAVOR);
   }
 
-  /** Returns the download {@link Cache}. */
+  /** Returns the download manager used by the application. */
-  public synchronized Cache getDownloadCache() {
+  public synchronized DownloadManager getDownloadManager() {
+    if (downloadManager == null) {
+      DownloaderConstructorHelper constructorHelper =
+          new DownloaderConstructorHelper(getDownloadCache(), buildHttpDataSourceFactory(null));
+      downloadManager =
+          new DownloadManager(
+              constructorHelper,
+              MAX_SIMULTANEOUS_DOWNLOADS,
+              DownloadManager.DEFAULT_MIN_RETRY_COUNT,
+              new File(getDownloadDirectory(), DOWNLOAD_ACTION_FILE),
+              DOWNLOAD_DESERIALIZERS);
+    }
+    return downloadManager;
+  }
+
+  private synchronized Cache getDownloadCache() {
     if (downloadCache == null) {
       File downloadContentDirectory = new File(getDownloadDirectory(), DOWNLOAD_CONTENT_DIRECTORY);
       downloadCache = new SimpleCache(downloadContentDirectory, new NoOpCacheEvictor());
@@ -75,11 +107,6 @@ public class DemoApplication extends Application {
     return downloadCache;
   }
 
-  /** Returns the file in which active download actions should be saved. */
-  public synchronized File getDownloadActionFile() {
-    return new File(getDownloadDirectory(), DOWNLOAD_ACTION_FILE);
-  }
-
   private File getDownloadDirectory() {
     if (downloadDirectory == null) {
       downloadDirectory = getExternalFilesDir(null);
@@ -90,14 +117,14 @@ public class DemoApplication extends Application {
     return downloadDirectory;
   }
 
-  private static CacheDataSourceFactory createReadOnlyCacheDataSource(
+  private static CacheDataSourceFactory buildReadOnlyCacheDataSource(
       DefaultDataSourceFactory upstreamFactory, Cache cache) {
     return new CacheDataSourceFactory(
         cache,
         upstreamFactory,
         new FileDataSourceFactory(),
-        /*cacheWriteDataSinkFactory=*/ null,
+        /* cacheWriteDataSinkFactory= */ null,
         CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR,
-        /*eventListener=*/ null);
+        /* eventListener= */ null);
   }
 }

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoDownloadService.java

@@ -19,12 +19,7 @@ import android.app.Notification;
 import com.google.android.exoplayer2.offline.DownloadManager;
 import com.google.android.exoplayer2.offline.DownloadManager.TaskState;
 import com.google.android.exoplayer2.offline.DownloadService;
-import com.google.android.exoplayer2.offline.DownloaderConstructorHelper;
-import com.google.android.exoplayer2.offline.ProgressiveDownloadAction;
 import com.google.android.exoplayer2.scheduler.PlatformScheduler;
-import com.google.android.exoplayer2.source.dash.offline.DashDownloadAction;
-import com.google.android.exoplayer2.source.hls.offline.HlsDownloadAction;
-import com.google.android.exoplayer2.source.smoothstreaming.offline.SsDownloadAction;
 import com.google.android.exoplayer2.ui.DownloadNotificationUtil;
 import com.google.android.exoplayer2.util.NotificationUtil;
 import com.google.android.exoplayer2.util.Util;
@@ -36,8 +31,6 @@ public class DemoDownloadService extends DownloadService {
   private static final int JOB_ID = 1;
   private static final int FOREGROUND_NOTIFICATION_ID = 1;
 
-  private static DownloadManager downloadManager;
-
   public DemoDownloadService() {
     super(
         FOREGROUND_NOTIFICATION_ID,
@@ -48,23 +41,7 @@ public class DemoDownloadService extends DownloadService {
 
   @Override
   protected DownloadManager getDownloadManager() {
-    if (downloadManager == null) {
+    return ((DemoApplication) getApplication()).getDownloadManager();
-      DemoApplication application = (DemoApplication) getApplication();
-      DownloaderConstructorHelper constructorHelper =
-          new DownloaderConstructorHelper(
-              application.getDownloadCache(), application.buildHttpDataSourceFactory(null));
-      downloadManager =
-          new DownloadManager(
-              constructorHelper,
-              /* maxSimultaneousDownloads= */ 2,
-              DownloadManager.DEFAULT_MIN_RETRY_COUNT,
-              application.getDownloadActionFile(),
-              DashDownloadAction.DESERIALIZER,
-              HlsDownloadAction.DESERIALIZER,
-              SsDownloadAction.DESERIALIZER,
-              ProgressiveDownloadAction.DESERIALIZER);
-    }
-    return downloadManager;
   }
 
   @Override