Make it possible to disable DownloadService notifications

Issue: #4389

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=204728270

demos/main/src/main/AndroidManifest.xml

@@ -79,7 +79,7 @@
     <service android:name="com.google.android.exoplayer2.demo.DemoDownloadService"
         android:exported="false">
       <intent-filter>
-        <action android:name="com.google.android.exoplayer.downloadService.action.INIT"/>
+        <action android:name="com.google.android.exoplayer.downloadService.action.RESTART"/>
         <category android:name="android.intent.category.DEFAULT"/>
       </intent-filter>
     </service>

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadService.java

@@ -52,17 +52,12 @@ public abstract class DownloadService extends Service {
   private static final String ACTION_RESTART =
       "com.google.android.exoplayer.downloadService.action.RESTART";
 
-  /** Starts download tasks. */
-  private static final String ACTION_START_DOWNLOADS =
-      "com.google.android.exoplayer.downloadService.action.START_DOWNLOADS";
-
-  /** Stops download tasks. */
-  private static final String ACTION_STOP_DOWNLOADS =
-      "com.google.android.exoplayer.downloadService.action.STOP_DOWNLOADS";
-
   /** Key for the {@link DownloadAction} in an {@link #ACTION_ADD} intent. */
   public static final String KEY_DOWNLOAD_ACTION = "download_action";
 
+  /** Invalid foreground notification id which can be used to run the service in the background. */
+  public static final int FOREGROUND_NOTIFICATION_ID_NONE = 0;
+
   /**
    * Key for a boolean flag in any intent to indicate whether the service was started in the
    * foreground. If set, the service is guaranteed to call {@link #startForeground(int,
@@ -81,8 +76,10 @@ public abstract class DownloadService extends Service {
   // tasks the resume more quickly than when relying on the scheduler alone.
   private static final HashMap<Class<? extends DownloadService>, RequirementsHelper>
       requirementsHelpers = new HashMap<>();
+  private static final Requirements DEFAULT_REQUIREMENTS =
+      new Requirements(Requirements.NETWORK_TYPE_ANY, false, false);
 
-  private final ForegroundNotificationUpdater foregroundNotificationUpdater;
+  private final @Nullable ForegroundNotificationUpdater foregroundNotificationUpdater;
   private final @Nullable String channelId;
   private final @StringRes int channelName;
 
@@ -93,16 +90,28 @@ public abstract class DownloadService extends Service {
   private boolean taskRemoved;
 
   /**
-   * Creates a DownloadService with {@link #DEFAULT_FOREGROUND_NOTIFICATION_UPDATE_INTERVAL}.
+   * Creates a DownloadService.
    *
-   * @param foregroundNotificationId The notification id for the foreground notification, must not
+   * <p>If {@code foregroundNotificationId} is {@link #FOREGROUND_NOTIFICATION_ID_NONE} (value
-   *     be 0.
+   * {@value #FOREGROUND_NOTIFICATION_ID_NONE}) then the service runs in the background. No
+   * foreground notification is displayed and {@link #getScheduler()} isn't called.
+   *
+   * <p>If {@code foregroundNotificationId} isn't {@link #FOREGROUND_NOTIFICATION_ID_NONE} (value
+   * {@value #FOREGROUND_NOTIFICATION_ID_NONE}) the service runs in the foreground with {@link
+   * #DEFAULT_FOREGROUND_NOTIFICATION_UPDATE_INTERVAL}. In that case {@link
+   * #getForegroundNotification(TaskState[])} should be overridden in the subclass.
+   *
+   * @param foregroundNotificationId The notification id for the foreground notification, or {@link
+   *     #FOREGROUND_NOTIFICATION_ID_NONE} (value {@value #FOREGROUND_NOTIFICATION_ID_NONE})
    */
   protected DownloadService(int foregroundNotificationId) {
     this(foregroundNotificationId, DEFAULT_FOREGROUND_NOTIFICATION_UPDATE_INTERVAL);
   }
 
   /**
+   * Creates a DownloadService which will run in the foreground. {@link
+   * #getForegroundNotification(TaskState[])} should be overridden in the subclass.
+   *
    * @param foregroundNotificationId The notification id for the foreground notification, must not
    *     be 0.
    * @param foregroundNotificationUpdateInterval The maximum interval to update foreground
@@ -118,6 +127,9 @@ public abstract class DownloadService extends Service {
   }
 
   /**
+   * Creates a DownloadService which will run in the foreground. {@link
+   * #getForegroundNotification(TaskState[])} should be overridden in the subclass.
+   *
    * @param foregroundNotificationId The notification id for the foreground notification. Must not
    *     be 0.
    * @param foregroundNotificationUpdateInterval The maximum interval between updates to the
@@ -135,7 +147,9 @@ public abstract class DownloadService extends Service {
       @Nullable String channelId,
       @StringRes int channelName) {
     foregroundNotificationUpdater =
-        new ForegroundNotificationUpdater(
+        foregroundNotificationId == 0
+            ? null
+            : new ForegroundNotificationUpdater(
                 foregroundNotificationId, foregroundNotificationUpdateInterval);
     this.channelId = channelId;
     this.channelName = channelName;
@@ -237,7 +251,7 @@ public abstract class DownloadService extends Service {
     switch (intentAction) {
       case ACTION_INIT:
       case ACTION_RESTART:
-        // Do nothing. The RequirementsWatcher will start downloads when possible.
+        // Do nothing.
         break;
       case ACTION_ADD:
         byte[] actionData = intent.getByteArrayExtra(KEY_DOWNLOAD_ACTION);
@@ -251,21 +265,22 @@ public abstract class DownloadService extends Service {
           }
         }
         break;
-      case ACTION_STOP_DOWNLOADS:
-        downloadManager.stopDownloads();
-        break;
-      case ACTION_START_DOWNLOADS:
-        downloadManager.startDownloads();
-        break;
       case ACTION_RELOAD_REQUIREMENTS:
         stopWatchingRequirements();
-        maybeStartWatchingRequirements();
         break;
       default:
         Log.e(TAG, "Ignoring unrecognized action: " + intentAction);
         break;
     }
-    maybeStartWatchingRequirements();
+
+    Requirements requirements = getRequirements();
+    if (requirements.checkRequirements(this)) {
+      downloadManager.startDownloads();
+    } else {
+      downloadManager.stopDownloads();
+    }
+    maybeStartWatchingRequirements(requirements);
+
     if (downloadManager.isIdle()) {
       stop();
     }
@@ -281,7 +296,9 @@ public abstract class DownloadService extends Service {
   @Override
   public void onDestroy() {
     logd("onDestroy");
+    if (foregroundNotificationUpdater != null) {
       foregroundNotificationUpdater.stopPeriodicUpdates();
+    }
     downloadManager.removeListener(downloadManagerListener);
     maybeStopWatchingRequirements();
   }
@@ -312,11 +329,13 @@ public abstract class DownloadService extends Service {
    * device has network connectivity.
    */
   protected Requirements getRequirements() {
-    return new Requirements(Requirements.NETWORK_TYPE_ANY, false, false);
+    return DEFAULT_REQUIREMENTS;
   }
 
   /**
-   * Returns a notification to be displayed when this service running in the foreground.
+   * Should be overridden in the subclass if the service will be run in the foreground.
+   *
+   * <p>Returns a notification to be displayed when this service running in the foreground.
    *
    * <p>This method is called when there is a task state change and periodically while there are
    * active tasks. The periodic update interval can be set using {@link #DownloadService(int,
@@ -329,7 +348,11 @@ public abstract class DownloadService extends Service {
    * @param taskStates The states of all current tasks.
    * @return The foreground notification to display.
    */
-  protected abstract Notification getForegroundNotification(TaskState[] taskStates);
+  protected Notification getForegroundNotification(TaskState[] taskStates) {
+    throw new IllegalStateException(
+        getClass().getName()
+            + " is started in the foreground but getForegroundNotification() is not implemented.");
+  }
 
   /**
    * Called when the state of a task changes.
@@ -340,14 +363,14 @@ public abstract class DownloadService extends Service {
     // Do nothing.
   }
 
-  private void maybeStartWatchingRequirements() {
+  private void maybeStartWatchingRequirements(Requirements requirements) {
     if (downloadManager.getDownloadCount() == 0) {
       return;
     }
     Class<? extends DownloadService> clazz = getClass();
     RequirementsHelper requirementsHelper = requirementsHelpers.get(clazz);
     if (requirementsHelper == null) {
-      requirementsHelper = new RequirementsHelper(this, getRequirements(), getScheduler(), clazz);
+      requirementsHelper = new RequirementsHelper(this, requirements, getScheduler(), clazz);
       requirementsHelpers.put(clazz, requirementsHelper);
       requirementsHelper.start();
       logd("started watching requirements");
@@ -370,11 +393,13 @@ public abstract class DownloadService extends Service {
   }
 
   private void stop() {
+    if (foregroundNotificationUpdater != null) {
       foregroundNotificationUpdater.stopPeriodicUpdates();
       // Make sure startForeground is called before stopping. Workaround for [Internal: b/69424260].
       if (startedInForeground && Util.SDK_INT >= 26) {
         foregroundNotificationUpdater.showNotificationIfNotAlready();
       }
+    }
     if (Util.SDK_INT < 28 && taskRemoved) { // See [Internal: b/74248644].
       stopSelf();
       logd("stopSelf()");
@@ -398,18 +423,20 @@ public abstract class DownloadService extends Service {
   private final class DownloadManagerListener implements DownloadManager.Listener {
     @Override
     public void onInitialized(DownloadManager downloadManager) {
-      maybeStartWatchingRequirements();
+      maybeStartWatchingRequirements(getRequirements());
     }
 
     @Override
     public void onTaskStateChanged(DownloadManager downloadManager, TaskState taskState) {
       DownloadService.this.onTaskStateChanged(taskState);
+      if (foregroundNotificationUpdater != null) {
         if (taskState.state == TaskState.STATE_STARTED) {
           foregroundNotificationUpdater.startPeriodicUpdates();
         } else {
           foregroundNotificationUpdater.update();
         }
       }
+    }
 
     @Override
     public final void onIdle(DownloadManager downloadManager) {
@@ -497,7 +524,12 @@ public abstract class DownloadService extends Service {
 
     @Override
     public void requirementsMet(RequirementsWatcher requirementsWatcher) {
-      startServiceWithAction(DownloadService.ACTION_START_DOWNLOADS);
+      try {
+        notifyService();
+      } catch (Exception e) {
+        /* If we can't notify the service, don't stop the scheduler. */
+        return;
+      }
       if (scheduler != null) {
         scheduler.cancel();
       }
@@ -505,7 +537,11 @@ public abstract class DownloadService extends Service {
 
     @Override
     public void requirementsNotMet(RequirementsWatcher requirementsWatcher) {
-      startServiceWithAction(DownloadService.ACTION_STOP_DOWNLOADS);
+      try {
+        notifyService();
+      } catch (Exception e) {
+        /* Do nothing. The service isn't running anyway. */
+      }
       if (scheduler != null) {
         String servicePackage = context.getPackageName();
         boolean success = scheduler.schedule(requirements, servicePackage, ACTION_RESTART);
@@ -515,9 +551,14 @@ public abstract class DownloadService extends Service {
       }
     }
 
-    private void startServiceWithAction(String action) {
+    private void notifyService() throws Exception {
-      Intent intent = getIntent(context, serviceClass, action).putExtra(KEY_FOREGROUND, true);
+      Intent intent = getIntent(context, serviceClass, DownloadService.ACTION_INIT);
-      Util.startForegroundService(context, intent);
+      try {
+        context.startService(intent);
+      } catch (IllegalStateException e) {
+        /* startService will fail if the app is in the background and the service isn't running. */
+        throw new Exception(e);
+      }
     }
   }
 }

library/core/src/main/java/com/google/android/exoplayer2/scheduler/RequirementsWatcher.java

@@ -87,7 +87,7 @@ public final class RequirementsWatcher {
   public void start() {
     Assertions.checkNotNull(Looper.myLooper());
 
-    checkRequirements(true);
+    requirementsWereMet = requirements.checkRequirements(context);
 
     IntentFilter filter = new IntentFilter();
     if (requirements.getRequiredNetworkType() != Requirements.NETWORK_TYPE_NONE) {
@@ -158,14 +158,12 @@ public final class RequirementsWatcher {
     }
   }
 
-  private void checkRequirements(boolean force) {
+  private void checkRequirements() {
     boolean requirementsAreMet = requirements.checkRequirements(context);
-    if (!force) {
     if (requirementsAreMet == requirementsWereMet) {
       logd("requirementsAreMet is still " + requirementsAreMet);
       return;
     }
-    }
     requirementsWereMet = requirementsAreMet;
     if (requirementsAreMet) {
       logd("start job");
@@ -187,7 +185,7 @@ public final class RequirementsWatcher {
     public void onReceive(Context context, Intent intent) {
       if (!isInitialStickyBroadcast()) {
         logd(RequirementsWatcher.this + " received " + intent.getAction());
-        checkRequirements(false);
+        checkRequirements();
       }
     }
   }
@@ -198,14 +196,14 @@ public final class RequirementsWatcher {
     public void onAvailable(Network network) {
       super.onAvailable(network);
       logd(RequirementsWatcher.this + " NetworkCallback.onAvailable");
-      checkRequirements(false);
+      checkRequirements();
     }
 
     @Override
     public void onLost(Network network) {
       super.onLost(network);
       logd(RequirementsWatcher.this + " NetworkCallback.onLost");
-      checkRequirements(false);
+      checkRequirements();
     }
   }
 }

library/dash/src/test/java/com/google/android/exoplayer2/source/dash/offline/DownloadServiceDashTest.java

@@ -20,14 +20,12 @@ import static com.google.android.exoplayer2.source.dash.offline.DashDownloadTest
 import static com.google.android.exoplayer2.testutil.CacheAsserts.assertCacheEmpty;
 import static com.google.android.exoplayer2.testutil.CacheAsserts.assertCachedData;
 
-import android.app.Notification;
 import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.offline.DownloadAction;
 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.StreamKey;
@@ -52,7 +50,6 @@ import org.junit.Before;
 import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.mockito.Mockito;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
@@ -135,18 +132,12 @@ public class DownloadServiceDashTest {
             dashDownloadManager.startDownloads();
 
             dashDownloadService =
-                new DownloadService(/*foregroundNotificationId=*/ 1) {
+                new DownloadService(DownloadService.FOREGROUND_NOTIFICATION_ID_NONE) {
-
                   @Override
                   protected DownloadManager getDownloadManager() {
                     return dashDownloadManager;
                   }
 
-                  @Override
-                  protected Notification getForegroundNotification(TaskState[] taskStates) {
-                    return Mockito.mock(Notification.class);
-                  }
-
                   @Nullable
                   @Override
                   protected Scheduler getScheduler() {