Add onSeekProcessed callback to Player interface.

This is useful to determine when a seek request was processed by the player
and all playback state changes (mostly to BUFFERING) have been performed.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=170826793

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

@@ -209,6 +209,11 @@ import java.util.Locale;
     Log.d(TAG, "]");
   }
 
+  @Override
+  public void onSeekProcessed() {
+    Log.d(TAG, "seekProcessed");
+  }
+
   // MetadataOutput
 
   @Override

extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java

@@ -41,7 +41,6 @@ import com.google.android.gms.cast.framework.SessionManager;
 import com.google.android.gms.cast.framework.SessionManagerListener;
 import com.google.android.gms.cast.framework.media.RemoteMediaClient;
 import com.google.android.gms.cast.framework.media.RemoteMediaClient.MediaChannelResult;
-import com.google.android.gms.common.api.CommonStatusCodes;
 import com.google.android.gms.common.api.PendingResult;
 import com.google.android.gms.common.api.ResultCallback;
 import java.util.List;
@@ -115,6 +114,7 @@ public final class CastPlayer implements Player {
   private int currentWindowIndex;
   private boolean playWhenReady;
   private long lastReportedPositionMs;
+  private int pendingSeekCount;
   private int pendingSeekWindowIndex;
   private long pendingSeekPositionMs;
 
@@ -333,11 +333,16 @@ public final class CastPlayer implements Player {
       } else {
         remoteMediaClient.seek(positionMs).setResultCallback(seekResultCallback);
       }
+      pendingSeekCount++;
       pendingSeekWindowIndex = windowIndex;
       pendingSeekPositionMs = positionMs;
       for (EventListener listener : listeners) {
         listener.onPositionDiscontinuity(Player.DISCONTINUITY_REASON_SEEK);
       }
+    } else if (pendingSeekCount == 0) {
+      for (EventListener listener : listeners) {
+        listener.onSeekProcessed();
+      }
     }
   }
 
@@ -536,7 +541,7 @@ public final class CastPlayer implements Player {
       }
     }
     int currentWindowIndex = fetchCurrentWindowIndex(getMediaStatus());
-    if (this.currentWindowIndex != currentWindowIndex) {
+    if (this.currentWindowIndex != currentWindowIndex && pendingSeekCount == 0) {
       this.currentWindowIndex = currentWindowIndex;
       for (EventListener listener : listeners) {
         listener.onPositionDiscontinuity(DISCONTINUITY_REASON_PERIOD_TRANSITION);
@@ -831,18 +836,18 @@ public final class CastPlayer implements Player {
     @Override
     public void onResult(@NonNull MediaChannelResult result) {
       int statusCode = result.getStatus().getStatusCode();
-      if (statusCode == CastStatusCodes.REPLACED) {
+      if (statusCode != CastStatusCodes.SUCCESS && statusCode != CastStatusCodes.REPLACED) {
-        // A seek was executed before this one completed. Do nothing.
-      } else {
-        pendingSeekWindowIndex = C.INDEX_UNSET;
-        pendingSeekPositionMs = C.TIME_UNSET;
-        if (statusCode != CommonStatusCodes.SUCCESS) {
         Log.e(TAG, "Seek failed. Error code " + statusCode + ": "
             + CastUtils.getLogString(statusCode));
       }
+      if (--pendingSeekCount == 0) {
+        pendingSeekWindowIndex = C.INDEX_UNSET;
+        pendingSeekPositionMs = C.TIME_UNSET;
+        for (EventListener listener : listeners) {
+          listener.onSeekProcessed();
+        }
       }
     }
-
   }
 
 }

library/core/src/androidTest/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -28,6 +28,8 @@ import com.google.android.exoplayer2.testutil.FakeRenderer;
 import com.google.android.exoplayer2.testutil.FakeShuffleOrder;
 import com.google.android.exoplayer2.testutil.FakeTimeline;
 import com.google.android.exoplayer2.testutil.FakeTimeline.TimelineWindowDefinition;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.CountDownLatch;
 import junit.framework.TestCase;
 
@@ -259,4 +261,38 @@ public final class ExoPlayerTest extends TestCase {
     assertTrue(renderer.isEnded);
   }
 
+  public void testSeekProcessedCallback() throws Exception {
+    Timeline timeline = new FakeTimeline(
+        new TimelineWindowDefinition(true, false, 100000),
+        new TimelineWindowDefinition(true, false, 100000));
+    ActionSchedule actionSchedule = new ActionSchedule.Builder("testSeekProcessedCallback")
+        // Initial seek before timeline preparation finished.
+        .pause().seek(10).waitForPlaybackState(Player.STATE_READY)
+        // Re-seek to same position, start playback and wait until playback reaches second window.
+        .seek(10).play().waitForPositionDiscontinuity()
+        // Seek twice in concession, expecting the first seek to be replaced.
+        .seek(5).seek(60).build();
+    final List<Integer> playbackStatesWhenSeekProcessed = new ArrayList<>();
+    Player.EventListener eventListener = new Player.DefaultEventListener() {
+      private int currentPlaybackState = Player.STATE_IDLE;
+
+      @Override
+      public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
+        currentPlaybackState = playbackState;
+      }
+
+      @Override
+      public void onSeekProcessed() {
+        playbackStatesWhenSeekProcessed.add(currentPlaybackState);
+      }
+    };
+    new ExoPlayerTestRunner.Builder()
+        .setTimeline(timeline).setEventListener(eventListener).setActionSchedule(actionSchedule)
+        .build().start().blockUntilEnded(TIMEOUT_MS);
+    assertEquals(3, playbackStatesWhenSeekProcessed.size());
+    assertEquals(Player.STATE_BUFFERING, (int) playbackStatesWhenSeekProcessed.get(0));
+    assertEquals(Player.STATE_READY, (int) playbackStatesWhenSeekProcessed.get(1));
+    assertEquals(Player.STATE_BUFFERING, (int) playbackStatesWhenSeekProcessed.get(2));
+  }
+
 }

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

@@ -482,10 +482,11 @@ import java.util.concurrent.CopyOnWriteArraySet;
             maskingWindowIndex = 0;
             maskingWindowPositionMs = 0;
           }
-          if (msg.arg1 != 0) {
           for (Player.EventListener listener : listeners) {
-              listener.onPositionDiscontinuity(DISCONTINUITY_REASON_SEEK);
+            if (msg.arg1 != 0) {
+              listener.onPositionDiscontinuity(DISCONTINUITY_REASON_INTERNAL);
             }
+            listener.onSeekProcessed();
           }
         }
         break;
@@ -516,6 +517,11 @@ import java.util.concurrent.CopyOnWriteArraySet;
             listener.onTimelineChanged(timeline, manifest);
           }
         }
+        if (pendingSeekAcks == 0 && sourceInfo.seekAcks > 0) {
+          for (Player.EventListener listener : listeners) {
+            listener.onSeekProcessed();
+          }
+        }
         break;
       }
       case ExoPlayerImplInternal.MSG_PLAYBACK_PARAMETERS_CHANGED: {

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

@@ -701,12 +701,12 @@ import java.io.IOException;
           timeline.getFirstWindowIndex(shuffleModeEnabled), window).firstPeriodIndex;
       // The seek position was valid for the timeline that it was performed into, but the
       // timeline has changed and a suitable seek position could not be resolved in the new one.
-      playbackInfo = new PlaybackInfo(firstPeriodIndex, 0);
-      eventHandler.obtainMessage(MSG_SEEK_ACK, 1, 0, playbackInfo).sendToTarget();
       // Set the internal position to (firstPeriodIndex,TIME_UNSET) so that a subsequent seek to
       // (firstPeriodIndex,0) isn't ignored.
       playbackInfo = new PlaybackInfo(firstPeriodIndex, C.TIME_UNSET);
       setState(Player.STATE_ENDED);
+      eventHandler.obtainMessage(MSG_SEEK_ACK, 1, 0, new PlaybackInfo(firstPeriodIndex, 0))
+          .sendToTarget();
       // Reset, but retain the source so that it can still be used should a seek occur.
       resetInternal(false);
       return;
@@ -1031,7 +1031,7 @@ import java.io.IOException;
           MediaPeriodId periodId =
               mediaPeriodInfoSequence.resolvePeriodPositionForAds(periodIndex, positionUs);
           playbackInfo = new PlaybackInfo(periodId, periodId.isAd() ? 0 : positionUs, positionUs);
-          notifySourceInfoRefresh(manifest, processedInitialSeekCount);
+          notifySourceInfoRefresh(manifest, playbackInfo, processedInitialSeekCount);
         }
       } else if (playbackInfo.startPositionUs == C.TIME_UNSET) {
         if (timeline.isEmpty()) {
@@ -1182,22 +1182,23 @@ import java.io.IOException;
       int processedInitialSeekCount) {
     int firstPeriodIndex = timeline.isEmpty() ? 0 : timeline.getWindow(
         timeline.getFirstWindowIndex(shuffleModeEnabled), window).firstPeriodIndex;
-    // Set the playback position to (firstPeriodIndex,0) for notifying the eventHandler.
-    playbackInfo = new PlaybackInfo(firstPeriodIndex, 0);
-    notifySourceInfoRefresh(manifest, processedInitialSeekCount);
     // Set the internal position to (firstPeriodIndex,TIME_UNSET) so that a subsequent seek to
     // (firstPeriodIndex,0) isn't ignored.
     playbackInfo = new PlaybackInfo(firstPeriodIndex, C.TIME_UNSET);
     setState(Player.STATE_ENDED);
+    // Set the playback position to (firstPeriodIndex,0) for notifying the eventHandler.
+    notifySourceInfoRefresh(manifest, new PlaybackInfo(firstPeriodIndex, 0),
+        processedInitialSeekCount);
     // Reset, but retain the source so that it can still be used should a seek occur.
     resetInternal(false);
   }
 
   private void notifySourceInfoRefresh(Object manifest) {
-    notifySourceInfoRefresh(manifest, 0);
+    notifySourceInfoRefresh(manifest, playbackInfo, 0);
   }
 
-  private void notifySourceInfoRefresh(Object manifest, int processedInitialSeekCount) {
+  private void notifySourceInfoRefresh(Object manifest, PlaybackInfo playbackInfo,
+      int processedInitialSeekCount) {
     eventHandler.obtainMessage(MSG_SOURCE_INFO_REFRESHED,
         new SourceInfo(timeline, manifest, playbackInfo, processedInitialSeekCount)).sendToTarget();
   }

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

@@ -134,6 +134,13 @@ public interface Player {
      */
     void onPlaybackParametersChanged(PlaybackParameters playbackParameters);
 
+    /**
+     * Called when all pending seek requests have been processed by the player. This is guaranteed
+     * to happen after any necessary changes to the player state were reported to
+     * {@link #onPlayerStateChanged(boolean, int)}.
+     */
+    void onSeekProcessed();
+
   }
 
   /**
@@ -186,6 +193,11 @@ public interface Player {
       // Do nothing.
     }
 
+    @Override
+    public void onSeekProcessed() {
+      // Do nothing.
+    }
+
   }
 
   /**