Take care playback preparer and queue navigator can not register overlapping

playback actions.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=162736210

extensions/mediasession/src/main/java/com/google/android/exoplayer2/ext/mediasession/DefaultPlaybackController.java

+/*
+ * Copyright (c) 2017 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.ext.mediasession;
+
+import android.support.v4.media.session.PlaybackStateCompat;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Player;
+
+/**
+ * A default implementation of the {@link MediaSessionConnector.PlaybackController}. You can safely
+ * override any method for instance to intercept calls for a given action.
+ */
+public class DefaultPlaybackController implements MediaSessionConnector.PlaybackController {
+
+  private static final long BASE_ACTIONS = PlaybackStateCompat.ACTION_PLAY_PAUSE
+      | PlaybackStateCompat.ACTION_PLAY | PlaybackStateCompat.ACTION_PAUSE
+      | PlaybackStateCompat.ACTION_STOP;
+
+  protected final long fastForwardIncrementMs;
+  protected final long rewindIncrementMs;
+
+  /**
+   * Creates a new {@link DefaultPlaybackController}. This is equivalent to calling
+   * {@code DefaultPlaybackController(15000L, 5000L)}.
+   */
+  public DefaultPlaybackController() {
+    this(15000L, 5000L);
+  }
+
+  /**
+   * Creates a new {@link DefaultPlaybackController} and sets the fast forward and rewind increments
+   * in milliseconds.
+   *
+   * @param fastForwardIncrementMs A positive value will cause the
+   *     {@link PlaybackStateCompat#ACTION_FAST_FORWARD} playback action to be added. A zero or a
+   *     negative value will cause it to be removed.
+   * @param rewindIncrementMs A positive value will cause the
+   *     {@link PlaybackStateCompat#ACTION_REWIND} playback action to be added. A zero or a
+   *     negative value will cause it to be removed.
+   */
+  public DefaultPlaybackController(long fastForwardIncrementMs, long rewindIncrementMs) {
+    this.fastForwardIncrementMs = fastForwardIncrementMs;
+    this.rewindIncrementMs = rewindIncrementMs;
+  }
+
+  @Override
+  public long getSupportedPlaybackActions(Player player) {
+    if (player == null || player.getCurrentTimeline().isEmpty()) {
+      return 0;
+    }
+    long actions = BASE_ACTIONS;
+    if (player.isCurrentWindowSeekable()) {
+      actions |= PlaybackStateCompat.ACTION_SEEK_TO;
+    }
+    if (fastForwardIncrementMs > 0) {
+      actions |= PlaybackStateCompat.ACTION_FAST_FORWARD;
+    }
+    if (rewindIncrementMs > 0) {
+      actions |= PlaybackStateCompat.ACTION_REWIND;
+    }
+    return actions;
+  }
+
+  @Override
+  public void onPlay(Player player) {
+    player.setPlayWhenReady(true);
+  }
+
+  @Override
+  public void onPause(Player player) {
+    player.setPlayWhenReady(false);
+  }
+
+  @Override
+  public void onSeekTo(Player player, long position) {
+    long duration = player.getDuration();
+    if (duration != C.TIME_UNSET) {
+      position = Math.min(position, duration);
+    }
+    player.seekTo(Math.max(position, 0));
+  }
+
+  @Override
+  public void onFastForward(Player player) {
+    if (fastForwardIncrementMs <= 0) {
+      return;
+    }
+    onSeekTo(player, player.getCurrentPosition() + fastForwardIncrementMs);
+  }
+
+  @Override
+  public void onRewind(Player player) {
+    if (rewindIncrementMs <= 0) {
+      return;
+    }
+    onSeekTo(player, player.getCurrentPosition() - rewindIncrementMs);
+  }
+
+  @Override
+  public void onStop(Player player) {
+    player.stop();
+  }
+
+}

extensions/mediasession/src/main/java/com/google/android/exoplayer2/ext/mediasession/TimelineQueueNavigator.java

@@ -39,7 +39,7 @@ public abstract class TimelineQueueNavigator implements MediaSessionConnector.Qu
   public static final int DEFAULT_MAX_QUEUE_SIZE = 10;
 
   private final MediaSessionCompat mediaSession;
-  private final int maxQueueSize;
+  protected final int maxQueueSize;
 
   private long activeQueueItemId;
 
@@ -80,19 +80,42 @@ public abstract class TimelineQueueNavigator implements MediaSessionConnector.Qu
    */
   public abstract MediaDescriptionCompat getMediaDescription(int windowIndex);
 
+  /**
+   * Supports the following media actions: {@code PlaybackStateCompat.ACTION_SKIP_TO_NEXT |
+   * PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS | PlaybackStateCompat.ACTION_SKIP_TO_QUEUE_ITEM}.
+   *
+   * @return The bit mask of the supported media actions.
+   */
   @Override
-  public long getSupportedPlaybackActions() {
-    return PlaybackStateCompat.ACTION_SKIP_TO_NEXT | PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS
-        | PlaybackStateCompat.ACTION_SKIP_TO_QUEUE_ITEM;
+  public long getSupportedQueueNavigatorActions(Player player) {
+    if (player == null || player.getCurrentTimeline().getWindowCount() < 2) {
+      return 0;
+    }
+    if (player.getRepeatMode() != Player.REPEAT_MODE_OFF) {
+      return PlaybackStateCompat.ACTION_SKIP_TO_NEXT | PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS
+          | PlaybackStateCompat.ACTION_SKIP_TO_QUEUE_ITEM;
+    }
+
+    int currentWindowIndex = player.getCurrentWindowIndex();
+    long actions;
+    if (currentWindowIndex == 0) {
+      actions = PlaybackStateCompat.ACTION_SKIP_TO_NEXT;
+    } else if (currentWindowIndex == player.getCurrentTimeline().getWindowCount() - 1) {
+      actions = PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS;
+    } else {
+      actions = PlaybackStateCompat.ACTION_SKIP_TO_NEXT
+          | PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS;
+    }
+    return actions | PlaybackStateCompat.ACTION_SKIP_TO_QUEUE_ITEM;
   }
 
   @Override
-  public void onTimelineChanged(Player player) {
+  public final void onTimelineChanged(Player player) {
     publishFloatingQueueWindow(player);
   }
 
   @Override
-  public void onCurrentWindowIndexChanged(Player player) {
+  public final void onCurrentWindowIndexChanged(Player player) {
     if (activeQueueItemId == MediaSessionCompat.QueueItem.UNKNOWN_ID
         || player.getCurrentTimeline().getWindowCount() > maxQueueSize) {
       publishFloatingQueueWindow(player);
@@ -107,7 +130,7 @@ public abstract class TimelineQueueNavigator implements MediaSessionConnector.Qu
   }
 
   @Override
-  public final void onSkipToPrevious(Player player) {
+  public void onSkipToPrevious(Player player) {
     Timeline timeline = player.getCurrentTimeline();
     if (timeline.isEmpty()) {
       return;
@@ -123,7 +146,7 @@ public abstract class TimelineQueueNavigator implements MediaSessionConnector.Qu
   }
 
   @Override
-  public final void onSkipToQueueItem(Player player, long id) {
+  public void onSkipToQueueItem(Player player, long id) {
     Timeline timeline = player.getCurrentTimeline();
     if (timeline.isEmpty()) {
       return;
@@ -135,7 +158,7 @@ public abstract class TimelineQueueNavigator implements MediaSessionConnector.Qu
   }
 
   @Override
-  public final void onSkipToNext(Player player) {
+  public void onSkipToNext(Player player) {
     Timeline timeline = player.getCurrentTimeline();
     if (timeline.isEmpty()) {
       return;