add a PlayerNotificationManager to post media style notifications.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188352116

.gitignore

@@ -43,6 +43,9 @@ cmake-build-debug
 dist
 tmp
 
+# External native builds
+.externalNativeBuild
+
 # VP9 extension
 extensions/vp9/src/main/jni/libvpx
 extensions/vp9/src/main/jni/libvpx_android_configs
@@ -62,3 +65,4 @@ extensions/cronet/jniLibs/*
 !extensions/cronet/jniLibs/README.md
 extensions/cronet/libs/*
 !extensions/cronet/libs/README.md
+

RELEASENOTES.md

@@ -35,6 +35,7 @@
   header ([#3926](https://github.com/google/ExoPlayer/issues/3926)).
 * Video: force rendering a frame periodically in `MediaCodecVideoRenderer` and
   `LibvpxVideoRenderer`, even if it is late.
+* Add PlayerNotificationManager.
 
 ### 2.7.0 ###
 

library/core/src/main/java/com/google/android/exoplayer2/ControlDispatcher.java

@@ -64,4 +64,12 @@ public interface ControlDispatcher {
    */
   boolean dispatchSetShuffleModeEnabled(Player player, boolean shuffleModeEnabled);
 
+  /**
+   * Dispatches a {@link Player#stop()} operation.
+   *
+   * @param player The {@link Player} to which the operation should be dispatched.
+   * @param reset Whether the player should be reset.
+   * @return True if the operation was dispatched. False if suppressed.
+   */
+  boolean dispatchStop(Player player, boolean reset);
 }

library/core/src/main/java/com/google/android/exoplayer2/DefaultControlDispatcher.java

@@ -47,4 +47,9 @@ public class DefaultControlDispatcher implements ControlDispatcher {
     return true;
   }
 
+  @Override
+  public boolean dispatchStop(Player player, boolean reset) {
+    player.stop(reset);
+    return true;
+  }
 }

library/ui/build.gradle

@@ -34,6 +34,7 @@ android {
 
 dependencies {
     implementation project(modulePrefix + 'library-core')
+    implementation 'com.android.support:support-media-compat:' + supportLibraryVersion
     implementation 'com.android.support:support-annotations:' + supportLibraryVersion
 }
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/PlayerNotificationManager.java

@@ -0,0 +1,931 @@
+/*
+ * Copyright (C) 2018 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.ui;
+
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+import android.app.Notification;
+import android.app.PendingIntent;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.graphics.Bitmap;
+import android.graphics.Color;
+import android.os.Handler;
+import android.os.Looper;
+import android.support.annotation.IntDef;
+import android.support.annotation.Nullable;
+import android.support.v4.app.NotificationCompat;
+import android.support.v4.app.NotificationManagerCompat;
+import android.support.v4.media.app.NotificationCompat.MediaStyle;
+import android.support.v4.media.session.MediaSessionCompat;
+import android.support.v4.util.Pair;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.ControlDispatcher;
+import com.google.android.exoplayer2.DefaultControlDispatcher;
+import com.google.android.exoplayer2.PlaybackParameters;
+import com.google.android.exoplayer2.Player;
+import com.google.android.exoplayer2.Timeline;
+import com.google.android.exoplayer2.util.Util;
+import java.lang.annotation.Retention;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A notification manager to start, update and cancel a media style notification reflecting the
+ * player state.
+ *
+ * <p>The notification is cancelled when {@code null} is passed to {@link #setPlayer(Player)} or
+ * when an intent with action {@link #ACTION_STOP} is received.
+ *
+ * <p>If the player is released it must be removed from the manager by calling {@code
+ * setPlayer(null)} which will cancel the notification.
+ *
+ * <h3>Action customization</h3>
+ *
+ * Standard playback actions can be shown or omitted as follows:
+ *
+ * <ul>
+ *   <li><b>{@code useNavigationActions}</b> - Sets whether the navigation previous and next actions
+ *       are displayed.
+ *       <ul>
+ *         <li>Corresponding setter: {@link #setUseNavigationActions(boolean)}
+ *       </ul>
+ *   <li><b>{@code stopAction}</b> - Sets which stop action should be used. If set to null, the stop
+ *       action is not displayed.
+ *       <ul>
+ *         <li>Corresponding setter: {@link #setStopAction(String)}}
+ *       </ul>
+ *   <li><b>{@code rewindIncrementMs}</b> - Sets the rewind increment. If set to zero the rewind
+ *       action is not displayed.
+ *       <ul>
+ *         <li>Corresponding setter: {@link #setRewindIncrementMs(long)}
+ *         <li>Default: {@link #DEFAULT_REWIND_MS} (5000)
+ *       </ul>
+ *   <li><b>{@code fastForwardIncrementMs}</b> - Sets the fast forward increment. If set to zero the
+ *       fast forward action is not included in the notification.
+ *       <ul>
+ *         <li>Corresponding setter: {@link #setFastForwardIncrementMs(long)}}
+ *         <li>Default: {@link #DEFAULT_FAST_FORWARD_MS} (5000)
+ *       </ul>
+ * </ul>
+ */
+public class PlayerNotificationManager {
+
+  /** An adapter to provide content assets of the media currently playing. */
+  public interface MediaDescriptionAdapter {
+
+    /**
+     * Gets the content title for the current media item.
+     *
+     * <p>See {@link NotificationCompat.Builder#setContentTitle(CharSequence)}.
+     *
+     * @param player The {@link Player} for which a notification is being built.
+     */
+    String getCurrentContentTitle(Player player);
+
+    /**
+     * Creates a content intent for the current media item.
+     *
+     * <p>See {@link NotificationCompat.Builder#setContentIntent(PendingIntent)}.
+     *
+     * @param player The {@link Player} for which a notification is being built.
+     */
+    @Nullable
+    PendingIntent createCurrentContentIntent(Player player);
+
+    /**
+     * Gets the content text for the current media item.
+     *
+     * <p>See {@link NotificationCompat.Builder#setContentText(CharSequence)}.
+     *
+     * @param player The {@link Player} for which a notification is being built.
+     */
+    @Nullable
+    String getCurrentContentText(Player player);
+
+    /**
+     * Gets the large icon for the current media item.
+     *
+     * <p>When a bitmap initially needs to be asynchronously loaded, a placeholder (or null) can be
+     * returned and the bitmap asynchronously passed to the {@link BitmapCallback} once it is
+     * loaded. Because the adapter may be called multiple times for the same media item, the bitmap
+     * should be cached by the app and whenever possible be returned synchronously at subsequent
+     * calls for the same media item.
+     *
+     * <p>See {@link NotificationCompat.Builder#setLargeIcon(Bitmap)}.
+     *
+     * @param player The {@link Player} for which a notification is being built.
+     * @param callback A {@link BitmapCallback} to provide a {@link Bitmap} asynchronously.
+     */
+    @Nullable
+    Bitmap getCurrentLargeIcon(Player player, BitmapCallback callback);
+  }
+
+  /** Defines and handles custom actions. */
+  public interface CustomActionReceiver {
+
+    /** Gets the actions handled by this receiver. */
+    Map<String, NotificationCompat.Action> createCustomActions(Context context);
+
+    /**
+     * Gets the actions to be included in the notification given the current player state.
+     *
+     * @param player The {@link Player} for which a notification is being built.
+     * @return The actions to be included in the notification.
+     */
+    List<String> getCustomActions(Player player);
+
+    /**
+     * Called when a custom action has been received.
+     *
+     * @param player The player.
+     * @param action The action from {@link Intent#getAction()}.
+     * @param intent The received {@link Intent}.
+     */
+    void onCustomAction(Player player, String action, Intent intent);
+  }
+
+  /** A listener for start and cancellation of the notification. */
+  public interface NotificationListener {
+
+    /**
+     * Called after the notification has been started.
+     *
+     * @param notificationId The id with which the notification has been posted.
+     * @param notification The {@link Notification}.
+     */
+    void onNotificationStarted(int notificationId, Notification notification);
+
+    /**
+     * Called after the notification has been cancelled.
+     *
+     * @param notificationId The id of the notification which has been cancelled.
+     */
+    void onNotificationCancelled(int notificationId);
+  }
+
+  /** Receives a {@link Bitmap}. */
+  public final class BitmapCallback {
+    private final int notificationTag;
+
+    /** Create the receiver. */
+    private BitmapCallback(int notificationTag) {
+      this.notificationTag = notificationTag;
+    }
+
+    /**
+     * Called when {@link Bitmap} is available.
+     *
+     * @param bitmap The bitmap to use as the large icon of the notification.
+     */
+    public void onBitmap(final Bitmap bitmap) {
+      if (bitmap != null) {
+        mainHandler.post(
+            new Runnable() {
+              @Override
+              public void run() {
+                if (notificationTag == currentNotificationTag && isNotificationStarted) {
+                  updateNotification(bitmap);
+                }
+              }
+            });
+      }
+    }
+  }
+
+  /** The action which starts playback. */
+  public static final String ACTION_PLAY = "com.google.android.exoplayer.play";
+  /** The action which pauses playback. */
+  public static final String ACTION_PAUSE = "com.google.android.exoplayer.pause";
+  /** The action which skips to the previous window. */
+  public static final String ACTION_PREVIOUS = "com.google.android.exoplayer.prev";
+  /** The action which skips to the next window. */
+  public static final String ACTION_NEXT = "com.google.android.exoplayer.next";
+  /** The action which fast forwards. */
+  public static final String ACTION_FAST_FORWARD = "com.google.android.exoplayer.ffwd";
+  /** The action which rewinds. */
+  public static final String ACTION_REWIND = "com.google.android.exoplayer.rewind";
+  /** The action which cancels the notification and stops playback. */
+  public static final String ACTION_STOP = "com.google.android.exoplayer.stop";
+
+  /** Visibility of notification on the lock screen. */
+  @Retention(SOURCE)
+  @IntDef({
+    NotificationCompat.VISIBILITY_PRIVATE,
+    NotificationCompat.VISIBILITY_PUBLIC,
+    NotificationCompat.VISIBILITY_SECRET
+  })
+  public @interface Visibility {}
+
+  /** The default fast forward increment, in milliseconds. */
+  public static final int DEFAULT_FAST_FORWARD_MS = 15000;
+  /** The default rewind increment, in milliseconds. */
+  public static final int DEFAULT_REWIND_MS = 5000;
+
+  private static final long MAX_POSITION_FOR_SEEK_TO_PREVIOUS = 3000;
+
+  private final Context context;
+  private final Handler mainHandler;
+  private final NotificationManagerCompat notificationManager;
+  private final IntentFilter intentFilter;
+  private final Player.EventListener playerListener;
+  private final NotificationBroadcastReceiver notificationBroadcastReceiver;
+  private final MediaDescriptionAdapter mediaDescriptionAdapter;
+  private final int notificationId;
+  private final String channelId;
+  private final Map<String, NotificationCompat.Action> playbackActions;
+  private final Map<String, NotificationCompat.Action> customActions;
+  private final CustomActionReceiver customActionReceiver;
+
+  private Player player;
+  private ControlDispatcher controlDispatcher;
+  private boolean isNotificationStarted;
+  private int currentNotificationTag;
+  private NotificationListener notificationListener;
+  private MediaSessionCompat.Token mediaSessionToken;
+  private boolean useNavigationActions;
+  private Pair<String, NotificationCompat.Action> stopAction;
+  private long fastForwardMs;
+  private long rewindMs;
+  private int badgeIconType;
+  private boolean colorized;
+  private int defaults;
+  private int color;
+  private int smallIconResourceId;
+  private int visibility;
+  private boolean ongoing;
+  private boolean useChronometer;
+  private boolean wasPlayWhenReady;
+  private int lastPlaybackState;
+
+  /**
+   * Creates the manager.
+   *
+   * @param context The {@link Context}.
+   * @param mediaDescriptionAdapter The {@link MediaDescriptionAdapter}.
+   * @param channelId The id of the notification channel.
+   * @param notificationId The id of the notification.
+   */
+  public PlayerNotificationManager(
+      Context context,
+      MediaDescriptionAdapter mediaDescriptionAdapter,
+      String channelId,
+      int notificationId) {
+    this(context, mediaDescriptionAdapter, channelId, notificationId, null);
+  }
+
+  /**
+   * Creates the manager with a {@link CustomActionReceiver}.
+   *
+   * @param context The {@link Context}.
+   * @param mediaDescriptionAdapter The {@link MediaDescriptionAdapter}.
+   * @param channelId The id of the notification channel.
+   * @param notificationId The id of the notification.
+   * @param customActionReceiver The {@link CustomActionReceiver}.
+   */
+  public PlayerNotificationManager(
+      Context context,
+      MediaDescriptionAdapter mediaDescriptionAdapter,
+      String channelId,
+      int notificationId,
+      @Nullable CustomActionReceiver customActionReceiver) {
+    this.context = context.getApplicationContext();
+    this.mediaDescriptionAdapter = mediaDescriptionAdapter;
+    this.channelId = channelId;
+    this.customActionReceiver = customActionReceiver;
+    this.notificationId = notificationId;
+    this.controlDispatcher = new DefaultControlDispatcher();
+    mainHandler = new Handler(Looper.getMainLooper());
+    notificationManager = NotificationManagerCompat.from(context);
+    playerListener = new PlayerListener();
+    notificationBroadcastReceiver = new NotificationBroadcastReceiver();
+    intentFilter = new IntentFilter();
+
+    // initialize actions
+    playbackActions = createPlaybackActions(context);
+    for (String action : playbackActions.keySet()) {
+      intentFilter.addAction(action);
+    }
+    customActions =
+        customActionReceiver != null
+            ? customActionReceiver.createCustomActions(context)
+            : Collections.<String, NotificationCompat.Action>emptyMap();
+    for (String action : customActions.keySet()) {
+      intentFilter.addAction(action);
+    }
+
+    setStopAction(ACTION_STOP);
+
+    useNavigationActions = true;
+    ongoing = true;
+    colorized = true;
+    useChronometer = true;
+    color = Color.TRANSPARENT;
+    smallIconResourceId = R.drawable.exo_notification_small_icon;
+    defaults = 0;
+    fastForwardMs = DEFAULT_FAST_FORWARD_MS;
+    rewindMs = DEFAULT_REWIND_MS;
+    setBadgeIconType(NotificationCompat.BADGE_ICON_SMALL);
+    setVisibility(NotificationCompat.VISIBILITY_PUBLIC);
+  }
+
+  /**
+   * Sets the {@link Player}.
+   *
+   * <p>Setting the player starts a notification immediately unless the player is in {@link
+   * Player#STATE_IDLE}, in which case the notification is started as soon as the player transitions
+   * away from being idle.
+   *
+   * <p>If the player is released it must be removed from the manager by calling {@code
+   * setPlayer(null)}. This will cancel the notification.
+   */
+  public final void setPlayer(Player player) {
+    if (this.player == player) {
+      return;
+    }
+    if (this.player != null) {
+      this.player.removeListener(playerListener);
+      if (player == null) {
+        stopNotification();
+      }
+    }
+    this.player = player;
+    if (player != null) {
+      wasPlayWhenReady = player.getPlayWhenReady();
+      lastPlaybackState = player.getPlaybackState();
+      player.addListener(playerListener);
+      if (lastPlaybackState != Player.STATE_IDLE) {
+        startOrUpdateNotification();
+      }
+    }
+  }
+
+  /**
+   * Sets the {@link ControlDispatcher}.
+   *
+   * @param controlDispatcher The {@link ControlDispatcher}, or null to use {@link
+   *     DefaultControlDispatcher}.
+   */
+  public final void setControlDispatcher(ControlDispatcher controlDispatcher) {
+    this.controlDispatcher =
+        controlDispatcher != null ? controlDispatcher : new DefaultControlDispatcher();
+  }
+
+  /**
+   * Sets the {@link NotificationListener}.
+   *
+   * @param notificationListener The {@link NotificationListener}.
+   */
+  public final void setNotificationListener(NotificationListener notificationListener) {
+    this.notificationListener = notificationListener;
+  }
+
+  /**
+   * Sets the fast forward increment in milliseconds.
+   *
+   * @param fastForwardMs The fast forward increment in milliseconds. A value of zero will cause the
+   *     fast forward action to be disabled.
+   */
+  public final void setFastForwardIncrementMs(long fastForwardMs) {
+    if (this.fastForwardMs == fastForwardMs) {
+      return;
+    }
+    this.fastForwardMs = fastForwardMs;
+    maybeUpdateNotification();
+  }
+
+  /**
+   * Sets the rewind increment in milliseconds.
+   *
+   * @param rewindMs The rewind increment in milliseconds. A value of zero will cause the rewind
+   *     action to be disabled.
+   */
+  public final void setRewindIncrementMs(long rewindMs) {
+    if (this.rewindMs == rewindMs) {
+      return;
+    }
+    this.rewindMs = rewindMs;
+    maybeUpdateNotification();
+  }
+
+  /**
+   * Sets whether the navigation actions should be used.
+   *
+   * @param useNavigationActions Whether to use navigation actions or not.
+   */
+  public final void setUseNavigationActions(boolean useNavigationActions) {
+    if (this.useNavigationActions != useNavigationActions) {
+      this.useNavigationActions = useNavigationActions;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the name of the action to be used as stop action to cancel the notification. If {@code
+   * null} is passed the stop action is not displayed.
+   *
+   * @param stopAction The name of the stop action which must be {@link #ACTION_STOP} or an action
+   *     provided by the {@link CustomActionReceiver}. {@code null} to omit the stop action.
+   */
+  public final void setStopAction(@Nullable String stopAction) {
+    if ((this.stopAction == null && stopAction == null)
+        || (this.stopAction != null && this.stopAction.first.equals(stopAction))) {
+      return;
+    }
+    if (stopAction == null) {
+      this.stopAction = null;
+    } else if (ACTION_STOP.equals(stopAction)) {
+      this.stopAction = new Pair<>(stopAction, playbackActions.get(ACTION_STOP));
+    } else if (customActions.containsKey(stopAction)) {
+      this.stopAction = new Pair<>(stopAction, customActions.get(stopAction));
+    } else {
+      throw new IllegalArgumentException();
+    }
+    maybeUpdateNotification();
+  }
+
+  /**
+   * Sets the {@link MediaSessionCompat.Token}.
+   *
+   * @param token The {@link MediaSessionCompat.Token}.
+   */
+  public final void setMediaSessionToken(MediaSessionCompat.Token token) {
+    if (!Util.areEqual(this.mediaSessionToken, token)) {
+      mediaSessionToken = token;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the badge icon type of the notification.
+   *
+   * <p>See {@link NotificationCompat.Builder#setBadgeIconType(int)}.
+   *
+   * @param badgeIconType The badge icon type.
+   */
+  public final void setBadgeIconType(@NotificationCompat.BadgeIconType int badgeIconType) {
+    if (this.badgeIconType == badgeIconType) {
+      return;
+    }
+    switch (badgeIconType) {
+      case NotificationCompat.BADGE_ICON_NONE:
+      case NotificationCompat.BADGE_ICON_SMALL:
+      case NotificationCompat.BADGE_ICON_LARGE:
+        this.badgeIconType = badgeIconType;
+        break;
+      default:
+        throw new IllegalArgumentException();
+    }
+    maybeUpdateNotification();
+  }
+
+  /**
+   * Sets whether the notification should be colorized (whether the notification color should be
+   * applied).
+   *
+   * <p>See {@link NotificationCompat.Builder#setColorized(boolean)}.
+   *
+   * @param colorized Whether to colorize the notification.
+   */
+  public final void setColorized(boolean colorized) {
+    if (this.colorized != colorized) {
+      this.colorized = colorized;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the defaults.
+   *
+   * <p>See {@link NotificationCompat.Builder#setDefaults(int)}.
+   *
+   * @param defaults The default notification options.
+   */
+  public final void setDefaults(int defaults) {
+    if (this.defaults != defaults) {
+      this.defaults = defaults;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the color of the notification as a color value like for instance solid {@link
+   * Color#BLACK)}. When set to {@link Color#TRANSPARENT} and a large icon is provided the
+   * notification is colored with a color taken from the palette if the icon (when a media session
+   * token is provided).
+   *
+   * <p>See {@link NotificationCompat.Builder#setColor(int)}.
+   *
+   * @param color The color.
+   */
+  public final void setColor(int color) {
+    if (this.color != color) {
+      this.color = color;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets whether the notification should be ongoing. If {@code false} the user can dismiss the
+   * notification by swiping. If in addition the stop action is enabled dismissing the notification
+   * triggers the stop action.
+   *
+   * <p>See {@link NotificationCompat.Builder#setOngoing(boolean)}.
+   *
+   * @param ongoing Whether {@code true} the notification is ongoing and not dismissible.
+   */
+  public final void setOngoing(boolean ongoing) {
+    if (this.ongoing != ongoing) {
+      this.ongoing = ongoing;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the small icon of the notification which is also shown in the system status bar.
+   *
+   * <p>See {@link NotificationCompat.Builder#setSmallIcon(int)}.
+   *
+   * @param smallIconResourceId The resource id of the small icon.
+   */
+  public final void setSmallIcon(int smallIconResourceId) {
+    if (this.smallIconResourceId != smallIconResourceId) {
+      this.smallIconResourceId = smallIconResourceId;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets whether the elapsed time of the media playback should be displayed
+   *
+   * <p>See {@link NotificationCompat.Builder#setUsesChronometer(boolean)}.
+   *
+   * @param useChronometer Whether to use chronometer.
+   */
+  public final void setUseChronometer(boolean useChronometer) {
+    if (this.useChronometer != useChronometer) {
+      this.useChronometer = useChronometer;
+      maybeUpdateNotification();
+    }
+  }
+
+  /**
+   * Sets the visibility of the notification which determines whether and how the notification is
+   * shown when the device is in lock screen mode.
+   *
+   * <p>See {@link NotificationCompat.Builder#setVisibility(int)}.
+   *
+   * @param visibility The visibility which must be one of {@link
+   *     NotificationCompat#VISIBILITY_PUBLIC}, {@link NotificationCompat#VISIBILITY_PRIVATE} or
+   *     {@link NotificationCompat#VISIBILITY_SECRET}.
+   */
+  public final void setVisibility(@Visibility int visibility) {
+    if (this.visibility == visibility) {
+      return;
+    }
+    switch (visibility) {
+      case NotificationCompat.VISIBILITY_PRIVATE:
+      case NotificationCompat.VISIBILITY_PUBLIC:
+      case NotificationCompat.VISIBILITY_SECRET:
+        this.visibility = visibility;
+        break;
+      default:
+        throw new IllegalStateException();
+    }
+    maybeUpdateNotification();
+  }
+
+  private Notification updateNotification(Bitmap bitmap) {
+    Notification notification = createNotification(player, bitmap);
+    notificationManager.notify(notificationId, notification);
+    return notification;
+  }
+
+  private void startOrUpdateNotification() {
+    Notification notification = updateNotification(null);
+    if (!isNotificationStarted) {
+      isNotificationStarted = true;
+      context.registerReceiver(notificationBroadcastReceiver, intentFilter);
+      if (notificationListener != null) {
+        notificationListener.onNotificationStarted(notificationId, notification);
+      }
+    }
+  }
+
+  private void maybeUpdateNotification() {
+    if (isNotificationStarted) {
+      updateNotification(null);
+    }
+  }
+
+  private void stopNotification() {
+    if (isNotificationStarted) {
+      notificationManager.cancel(notificationId);
+      isNotificationStarted = false;
+      context.unregisterReceiver(notificationBroadcastReceiver);
+      if (notificationListener != null) {
+        notificationListener.onNotificationCancelled(notificationId);
+      }
+    }
+  }
+
+  private Map<String, NotificationCompat.Action> createPlaybackActions(Context context) {
+    Map<String, NotificationCompat.Action> actions = new HashMap<>();
+    Intent playIntent = new Intent(ACTION_PLAY).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_PLAY,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_play,
+            context.getString(R.string.exo_controls_play_description),
+            PendingIntent.getBroadcast(context, 0, playIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent pauseIntent = new Intent(ACTION_PAUSE).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_PAUSE,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_pause,
+            context.getString(R.string.exo_controls_pause_description),
+            PendingIntent.getBroadcast(
+                context, 0, pauseIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent stopIntent = new Intent(ACTION_STOP).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_STOP,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_stop,
+            context.getString(R.string.exo_controls_stop_description),
+            PendingIntent.getBroadcast(context, 0, stopIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent rewindIntent = new Intent(ACTION_REWIND).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_REWIND,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_rewind,
+            context.getString(R.string.exo_controls_rewind_description),
+            PendingIntent.getBroadcast(
+                context, 0, rewindIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent fastForwardIntent = new Intent(ACTION_FAST_FORWARD).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_FAST_FORWARD,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_fastforward,
+            context.getString(R.string.exo_controls_fastforward_description),
+            PendingIntent.getBroadcast(
+                context, 0, fastForwardIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent previousIntent = new Intent(ACTION_PREVIOUS).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_PREVIOUS,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_previous,
+            context.getString(R.string.exo_controls_previous_description),
+            PendingIntent.getBroadcast(
+                context, 0, previousIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    Intent nextIntent = new Intent(ACTION_NEXT).setPackage(context.getPackageName());
+    actions.put(
+        ACTION_NEXT,
+        new NotificationCompat.Action(
+            R.drawable.exo_notification_next,
+            context.getString(R.string.exo_controls_next_description),
+            PendingIntent.getBroadcast(context, 0, nextIntent, PendingIntent.FLAG_CANCEL_CURRENT)));
+    return actions;
+  }
+
+  /**
+   * Creates the notification given the current player state.
+   *
+   * @param player The player for which state to build a notification.
+   * @param largeIcon The large icon to be used.
+   * @return The {@link Notification} which has been built.
+   */
+  protected Notification createNotification(Player player, @Nullable Bitmap largeIcon) {
+    boolean isPlayingAd = player.isPlayingAd();
+    NotificationCompat.Builder builder = new NotificationCompat.Builder(context, channelId);
+    List<String> actionNames = getActions(player);
+    for (int i = 0; i < actionNames.size(); i++) {
+      String actionName = actionNames.get(i);
+      NotificationCompat.Action action =
+          playbackActions.containsKey(actionName)
+              ? playbackActions.get(actionName)
+              : customActions.get(actionName);
+      if (action != null) {
+        builder.addAction(action);
+      }
+    }
+    // Create a media style notification.
+    MediaStyle mediaStyle = new MediaStyle();
+    builder.setStyle(mediaStyle);
+    if (mediaSessionToken != null) {
+      mediaStyle.setMediaSession(mediaSessionToken);
+    }
+    mediaStyle.setShowActionsInCompactView(getActionIndicesForCompactView(player));
+    // Configure stop action (eg. when user dismisses the notification when !isOngoing).
+    boolean useStopAction = stopAction != null && !isPlayingAd;
+    mediaStyle.setShowCancelButton(useStopAction);
+    if (useStopAction) {
+      PendingIntent stopIntent = stopAction.second.actionIntent;
+      builder.setDeleteIntent(stopIntent);
+      mediaStyle.setCancelButtonIntent(stopIntent);
+    }
+    // Set notification properties from getters.
+    builder
+        .setBadgeIconType(badgeIconType)
+        .setOngoing(ongoing)
+        .setColor(color)
+        .setColorized(colorized)
+        .setSmallIcon(smallIconResourceId)
+        .setVisibility(visibility)
+        .setDefaults(defaults);
+    if (useChronometer
+        && !player.isCurrentWindowDynamic()
+        && player.getPlayWhenReady()
+        && player.getPlaybackState() == Player.STATE_READY) {
+      builder
+          .setWhen(System.currentTimeMillis() - player.getContentPosition())
+          .setShowWhen(true)
+          .setUsesChronometer(true);
+    } else {
+      builder.setShowWhen(false).setUsesChronometer(false);
+    }
+    // Set media specific notification properties from MediaDescriptionAdapter.
+    builder.setContentTitle(mediaDescriptionAdapter.getCurrentContentTitle(player));
+    builder.setContentText(mediaDescriptionAdapter.getCurrentContentText(player));
+    if (largeIcon == null) {
+      largeIcon =
+          mediaDescriptionAdapter.getCurrentLargeIcon(
+              player, new BitmapCallback(++currentNotificationTag));
+    }
+    if (largeIcon != null) {
+      builder.setLargeIcon(largeIcon);
+    }
+    PendingIntent contentIntent = mediaDescriptionAdapter.createCurrentContentIntent(player);
+    if (contentIntent != null) {
+      builder.setContentIntent(contentIntent);
+    }
+    return builder.build();
+  }
+
+  /**
+   * Gets the names and order of the actions to be included in the notification at the current
+   * player state.
+   *
+   * <p>The playback and custom actions are combined and placed in the following order if not
+   * omitted:
+   *
+   * <pre>
+   *   +------------------------------------------------------------------------+
+   *   | prev | &lt;&lt; | play/pause | &gt;&gt; | next | custom actions | stop |
+   *   +------------------------------------------------------------------------+
+   * </pre>
+   *
+   * <p>This method can be safely overridden. However, the names must be of the playback actions
+   * {@link #ACTION_PAUSE}, {@link #ACTION_PLAY}, {@link #ACTION_FAST_FORWARD}, {@link
+   * #ACTION_REWIND}, {@link #ACTION_NEXT} or {@link #ACTION_PREVIOUS}, or a key contained in the
+   * map returned by {@link CustomActionReceiver#createCustomActions(Context)}. Otherwise the action
+   * name is ignored.
+   */
+  protected List<String> getActions(Player player) {
+    List<String> stringActions = new ArrayList<>();
+    if (!player.isPlayingAd()) {
+      if (useNavigationActions) {
+        stringActions.add(ACTION_PREVIOUS);
+      }
+      if (rewindMs > 0) {
+        stringActions.add(ACTION_REWIND);
+      }
+      if (player.getPlayWhenReady()) {
+        stringActions.add(ACTION_PAUSE);
+      } else if (!player.getPlayWhenReady()) {
+        stringActions.add(ACTION_PLAY);
+      }
+      if (fastForwardMs > 0) {
+        stringActions.add(ACTION_FAST_FORWARD);
+      }
+      if (useNavigationActions && player.getNextWindowIndex() != C.INDEX_UNSET) {
+        stringActions.add(ACTION_NEXT);
+      }
+      if (!customActions.isEmpty()) {
+        stringActions.addAll(customActionReceiver.getCustomActions(player));
+      }
+      if (stopAction != null) {
+        stringActions.add(stopAction.first);
+      }
+    }
+    return stringActions;
+  }
+
+  /**
+   * Gets an array with the indices of the buttons to be shown in compact mode.
+   *
+   * <p>This method can be overridden. The indices must refer to the list of actions returned by
+   * {@link #getActions(Player)}.
+   *
+   * @param player The player for which state to build a notification.
+   */
+  protected int[] getActionIndicesForCompactView(Player player) {
+    int actionIndex = useNavigationActions ? 1 : 0;
+    actionIndex += fastForwardMs > 0 ? 1 : 0;
+    return new int[] {actionIndex};
+  }
+
+  private class PlayerListener extends Player.DefaultEventListener {
+
+    @Override
+    public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
+      if ((wasPlayWhenReady != playWhenReady && playbackState != Player.STATE_IDLE)
+          || lastPlaybackState != playbackState) {
+        startOrUpdateNotification();
+      }
+      wasPlayWhenReady = playWhenReady;
+      lastPlaybackState = playbackState;
+    }
+
+    @Override
+    public void onTimelineChanged(Timeline timeline, Object manifest, int reason) {
+      if (player.getPlaybackState() == Player.STATE_IDLE) {
+        return;
+      }
+      startOrUpdateNotification();
+    }
+
+    @Override
+    public void onPlaybackParametersChanged(PlaybackParameters playbackParameters) {
+      if (player.getPlaybackState() == Player.STATE_IDLE) {
+        return;
+      }
+      startOrUpdateNotification();
+    }
+
+    @Override
+    public void onPositionDiscontinuity(int reason) {
+      startOrUpdateNotification();
+    }
+
+    @Override
+    public void onRepeatModeChanged(int repeatMode) {
+      if (player.getPlaybackState() == Player.STATE_IDLE) {
+        return;
+      }
+      startOrUpdateNotification();
+    }
+  }
+
+  private class NotificationBroadcastReceiver extends BroadcastReceiver {
+
+    private final Timeline.Window window;
+
+    /** Creates the broadcast receiver. */
+    public NotificationBroadcastReceiver() {
+      window = new Timeline.Window();
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+      if (!isNotificationStarted) {
+        return;
+      }
+      String action = intent.getAction();
+      if (ACTION_PLAY.equals(action) || ACTION_PAUSE.equals(action)) {
+        controlDispatcher.dispatchSetPlayWhenReady(player, ACTION_PLAY.equals(action));
+      } else if (ACTION_FAST_FORWARD.equals(action) || ACTION_REWIND.equals(action)) {
+        long increment = ACTION_FAST_FORWARD.equals(action) ? fastForwardMs : -rewindMs;
+        controlDispatcher.dispatchSeekTo(
+            player, player.getCurrentWindowIndex(), player.getCurrentPosition() + increment);
+      } else if (ACTION_NEXT.equals(action)) {
+        int nextWindowIndex = player.getNextWindowIndex();
+        if (nextWindowIndex != C.INDEX_UNSET) {
+          controlDispatcher.dispatchSeekTo(player, nextWindowIndex, C.TIME_UNSET);
+        }
+      } else if (ACTION_PREVIOUS.equals(action)) {
+        player.getCurrentTimeline().getWindow(player.getCurrentWindowIndex(), window);
+        int previousWindowIndex = player.getPreviousWindowIndex();
+        if (previousWindowIndex != C.INDEX_UNSET
+            && (player.getCurrentPosition() <= MAX_POSITION_FOR_SEEK_TO_PREVIOUS
+                || (window.isDynamic && !window.isSeekable))) {
+          controlDispatcher.dispatchSeekTo(player, previousWindowIndex, C.TIME_UNSET);
+        } else {
+          controlDispatcher.dispatchSeekTo(player, player.getCurrentWindowIndex(), C.TIME_UNSET);
+        }
+      } else if (ACTION_STOP.equals(action)) {
+        controlDispatcher.dispatchStop(player, true);
+        stopNotification();
+      } else if (customActions.containsKey(action)) {
+        customActionReceiver.onCustomAction(player, action, intent);
+      }
+    }
+  }
+}

library/ui/src/main/res/drawable-anydpi-v21/exo_icon_stop.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24"
+        android:viewportHeight="24">
+
+    <path
+        android:pathData="M0 0h24v24H0z" />
+    <path
+        android:fillColor="#000000"
+        android:pathData="M6 6h12v12H6z" />
+</vector>

library/ui/src/main/res/values/drawables.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <drawable name="exo_controls_play">@drawable/exo_icon_play</drawable>
+  <drawable name="exo_controls_pause">@drawable/exo_icon_pause</drawable>
+  <drawable name="exo_controls_next">@drawable/exo_icon_next</drawable>
+  <drawable name="exo_controls_previous">@drawable/exo_icon_previous</drawable>
+  <drawable name="exo_controls_fastforward">@drawable/exo_icon_fastforward</drawable>
+  <drawable name="exo_controls_rewind">@drawable/exo_icon_rewind</drawable>
+  <drawable name="exo_notification_play">@drawable/exo_icon_play</drawable>
+  <drawable name="exo_notification_pause">@drawable/exo_icon_pause</drawable>
+  <drawable name="exo_notification_next">@drawable/exo_icon_next</drawable>
+  <drawable name="exo_notification_previous">@drawable/exo_icon_previous</drawable>
+  <drawable name="exo_notification_fastforward">@drawable/exo_icon_fastforward</drawable>
+  <drawable name="exo_notification_rewind">@drawable/exo_icon_rewind</drawable>
+  <drawable name="exo_notification_stop">@drawable/exo_icon_stop</drawable>
+</resources>