Log warning with stack trace if player is accessed from the wrong thread.

This doesn't break apps which violate this policy. But it creates a clear
warning which is also likely to be reported in analytics tools.

Issue:#4463

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213442510

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

@@ -109,6 +109,7 @@ public class SimpleExoPlayer
   private List<Cue> currentCues;
   private VideoFrameMetadataListener videoFrameMetadataListener;
   private CameraMotionListener cameraMotionListener;
+  private boolean hasNotifiedFullWrongThreadWarning;
 
   /**
    * @param context A {@link Context}.
@@ -266,6 +267,7 @@ public class SimpleExoPlayer
    */
   @Override
   public void setVideoScalingMode(@C.VideoScalingMode int videoScalingMode) {
+    verifyApplicationThread();
     this.videoScalingMode = videoScalingMode;
     for (Renderer renderer : renderers) {
       if (renderer.getTrackType() == C.TRACK_TYPE_VIDEO) {
@@ -285,11 +287,13 @@ public class SimpleExoPlayer
 
   @Override
   public void clearVideoSurface() {
+    verifyApplicationThread();
     setVideoSurface(null);
   }
 
   @Override
   public void clearVideoSurface(Surface surface) {
+    verifyApplicationThread();
     if (surface != null && surface == this.surface) {
       setVideoSurface(null);
     }
@@ -297,6 +301,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setVideoSurface(@Nullable Surface surface) {
+    verifyApplicationThread();
     removeSurfaceCallbacks();
     setVideoSurfaceInternal(surface, false);
     int newSurfaceSize = surface == null ? 0 : C.LENGTH_UNSET;
@@ -305,6 +310,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setVideoSurfaceHolder(SurfaceHolder surfaceHolder) {
+    verifyApplicationThread();
     removeSurfaceCallbacks();
     this.surfaceHolder = surfaceHolder;
     if (surfaceHolder == null) {
@@ -326,6 +332,7 @@ public class SimpleExoPlayer
 
   @Override
   public void clearVideoSurfaceHolder(SurfaceHolder surfaceHolder) {
+    verifyApplicationThread();
     if (surfaceHolder != null && surfaceHolder == this.surfaceHolder) {
       setVideoSurfaceHolder(null);
     }
@@ -343,6 +350,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setVideoTextureView(TextureView textureView) {
+    verifyApplicationThread();
     removeSurfaceCallbacks();
     this.textureView = textureView;
     if (textureView == null) {
@@ -367,6 +375,7 @@ public class SimpleExoPlayer
 
   @Override
   public void clearVideoTextureView(TextureView textureView) {
+    verifyApplicationThread();
     if (textureView != null && textureView == this.textureView) {
       setVideoTextureView(null);
     }
@@ -389,6 +398,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setAudioAttributes(AudioAttributes audioAttributes, boolean handleAudioFocus) {
+    verifyApplicationThread();
     if (!Util.areEqual(this.audioAttributes, audioAttributes)) {
       this.audioAttributes = audioAttributes;
       for (Renderer renderer : renderers) {
@@ -424,6 +434,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setAuxEffectInfo(AuxEffectInfo auxEffectInfo) {
+    verifyApplicationThread();
     for (Renderer renderer : renderers) {
       if (renderer.getTrackType() == C.TRACK_TYPE_AUDIO) {
         player
@@ -442,6 +453,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setVolume(float audioVolume) {
+    verifyApplicationThread();
     audioVolume = Util.constrainValue(audioVolume, /* min= */ 0, /* max= */ 1);
     if (this.audioVolume == audioVolume) {
       return;
@@ -500,6 +512,7 @@ public class SimpleExoPlayer
    * @param listener The listener to be added.
    */
   public void addAnalyticsListener(AnalyticsListener listener) {
+    verifyApplicationThread();
     analyticsCollector.addListener(listener);
   }
 
@@ -509,6 +522,7 @@ public class SimpleExoPlayer
    * @param listener The listener to be removed.
    */
   public void removeAnalyticsListener(AnalyticsListener listener) {
+    verifyApplicationThread();
     analyticsCollector.removeListener(listener);
   }
 
@@ -571,6 +585,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setVideoFrameMetadataListener(VideoFrameMetadataListener listener) {
+    verifyApplicationThread();
     videoFrameMetadataListener = listener;
     for (Renderer renderer : renderers) {
       if (renderer.getTrackType() == C.TRACK_TYPE_VIDEO) {
@@ -585,6 +600,7 @@ public class SimpleExoPlayer
 
   @Override
   public void clearVideoFrameMetadataListener(VideoFrameMetadataListener listener) {
+    verifyApplicationThread();
     if (videoFrameMetadataListener != listener) {
       return;
     }
@@ -601,6 +617,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setCameraMotionListener(CameraMotionListener listener) {
+    verifyApplicationThread();
     cameraMotionListener = listener;
     for (Renderer renderer : renderers) {
       if (renderer.getTrackType() == C.TRACK_TYPE_CAMERA_MOTION) {
@@ -615,6 +632,7 @@ public class SimpleExoPlayer
 
   @Override
   public void clearCameraMotionListener(CameraMotionListener listener) {
+    verifyApplicationThread();
     if (cameraMotionListener != listener) {
       return;
     }
@@ -814,26 +832,31 @@ public class SimpleExoPlayer
 
   @Override
   public void addListener(Player.EventListener listener) {
+    verifyApplicationThread();
     player.addListener(listener);
   }
 
   @Override
   public void removeListener(Player.EventListener listener) {
+    verifyApplicationThread();
     player.removeListener(listener);
   }
 
   @Override
   public int getPlaybackState() {
+    verifyApplicationThread();
     return player.getPlaybackState();
   }
 
   @Override
   public @Nullable ExoPlaybackException getPlaybackError() {
+    verifyApplicationThread();
     return player.getPlaybackError();
   }
 
   @Override
   public void retry() {
+    verifyApplicationThread();
     if (mediaSource != null
         && (getPlaybackError() != null || getPlaybackState() == Player.STATE_IDLE)) {
       prepare(mediaSource, /* resetPosition= */ false, /* resetState= */ false);
@@ -847,6 +870,7 @@ public class SimpleExoPlayer
 
   @Override
   public void prepare(MediaSource mediaSource, boolean resetPosition, boolean resetState) {
+    verifyApplicationThread();
     if (this.mediaSource != null) {
       this.mediaSource.removeEventListener(analyticsCollector);
       analyticsCollector.resetForNewMediaSource();
@@ -861,6 +885,7 @@ public class SimpleExoPlayer
 
   @Override
   public void setPlayWhenReady(boolean playWhenReady) {
+    verifyApplicationThread();
     @AudioFocusManager.PlayerCommand
     int playerCommand = audioFocusManager.handleSetPlayWhenReady(playWhenReady, getPlaybackState());
     updatePlayWhenReady(playWhenReady, playerCommand);
@@ -868,80 +893,95 @@ public class SimpleExoPlayer
 
   @Override
   public boolean getPlayWhenReady() {
+    verifyApplicationThread();
     return player.getPlayWhenReady();
   }
 
   @Override
   public @RepeatMode int getRepeatMode() {
+    verifyApplicationThread();
     return player.getRepeatMode();
   }
 
   @Override
   public void setRepeatMode(@RepeatMode int repeatMode) {
+    verifyApplicationThread();
     player.setRepeatMode(repeatMode);
   }
 
   @Override
   public void setShuffleModeEnabled(boolean shuffleModeEnabled) {
+    verifyApplicationThread();
     player.setShuffleModeEnabled(shuffleModeEnabled);
   }
 
   @Override
   public boolean getShuffleModeEnabled() {
+    verifyApplicationThread();
     return player.getShuffleModeEnabled();
   }
 
   @Override
   public boolean isLoading() {
+    verifyApplicationThread();
     return player.isLoading();
   }
 
   @Override
   public void seekToDefaultPosition() {
+    verifyApplicationThread();
     analyticsCollector.notifySeekStarted();
     player.seekToDefaultPosition();
   }
 
   @Override
   public void seekToDefaultPosition(int windowIndex) {
+    verifyApplicationThread();
     analyticsCollector.notifySeekStarted();
     player.seekToDefaultPosition(windowIndex);
   }
 
   @Override
   public void seekTo(long positionMs) {
+    verifyApplicationThread();
     analyticsCollector.notifySeekStarted();
     player.seekTo(positionMs);
   }
 
   @Override
   public void seekTo(int windowIndex, long positionMs) {
+    verifyApplicationThread();
     analyticsCollector.notifySeekStarted();
     player.seekTo(windowIndex, positionMs);
   }
 
   @Override
   public void setPlaybackParameters(@Nullable PlaybackParameters playbackParameters) {
+    verifyApplicationThread();
     player.setPlaybackParameters(playbackParameters);
   }
 
   @Override
   public PlaybackParameters getPlaybackParameters() {
+    verifyApplicationThread();
     return player.getPlaybackParameters();
   }
 
   @Override
   public void setSeekParameters(@Nullable SeekParameters seekParameters) {
+    verifyApplicationThread();
     player.setSeekParameters(seekParameters);
   }
 
   @Override
   public SeekParameters getSeekParameters() {
+    verifyApplicationThread();
     return player.getSeekParameters();
   }
 
   @Override
   public @Nullable Object getCurrentTag() {
+    verifyApplicationThread();
     return player.getCurrentTag();
   }
 
@@ -952,6 +992,7 @@ public class SimpleExoPlayer
 
   @Override
   public void stop(boolean reset) {
+    verifyApplicationThread();
     player.stop(reset);
     if (mediaSource != null) {
       mediaSource.removeEventListener(analyticsCollector);
@@ -992,6 +1033,7 @@ public class SimpleExoPlayer
 
   @Override
   public PlayerMessage createMessage(PlayerMessage.Target target) {
+    verifyApplicationThread();
     return player.createMessage(target);
   }
 
@@ -1004,116 +1046,139 @@ public class SimpleExoPlayer
 
   @Override
   public int getRendererCount() {
+    verifyApplicationThread();
     return player.getRendererCount();
   }
 
   @Override
   public int getRendererType(int index) {
+    verifyApplicationThread();
     return player.getRendererType(index);
   }
 
   @Override
   public TrackGroupArray getCurrentTrackGroups() {
+    verifyApplicationThread();
     return player.getCurrentTrackGroups();
   }
 
   @Override
   public TrackSelectionArray getCurrentTrackSelections() {
+    verifyApplicationThread();
     return player.getCurrentTrackSelections();
   }
 
   @Override
   public Timeline getCurrentTimeline() {
+    verifyApplicationThread();
     return player.getCurrentTimeline();
   }
 
   @Override
   public @Nullable Object getCurrentManifest() {
+    verifyApplicationThread();
     return player.getCurrentManifest();
   }
 
   @Override
   public int getCurrentPeriodIndex() {
+    verifyApplicationThread();
     return player.getCurrentPeriodIndex();
   }
 
   @Override
   public int getCurrentWindowIndex() {
+    verifyApplicationThread();
     return player.getCurrentWindowIndex();
   }
 
   @Override
   public int getNextWindowIndex() {
+    verifyApplicationThread();
     return player.getNextWindowIndex();
   }
 
   @Override
   public int getPreviousWindowIndex() {
+    verifyApplicationThread();
     return player.getPreviousWindowIndex();
   }
 
   @Override
   public long getDuration() {
+    verifyApplicationThread();
     return player.getDuration();
   }
 
   @Override
   public long getCurrentPosition() {
+    verifyApplicationThread();
     return player.getCurrentPosition();
   }
 
   @Override
   public long getBufferedPosition() {
+    verifyApplicationThread();
     return player.getBufferedPosition();
   }
 
   @Override
   public int getBufferedPercentage() {
+    verifyApplicationThread();
     return player.getBufferedPercentage();
   }
 
   @Override
   public long getTotalBufferedDuration() {
+    verifyApplicationThread();
     return player.getTotalBufferedDuration();
   }
 
   @Override
   public boolean isCurrentWindowDynamic() {
+    verifyApplicationThread();
     return player.isCurrentWindowDynamic();
   }
 
   @Override
   public boolean isCurrentWindowSeekable() {
+    verifyApplicationThread();
     return player.isCurrentWindowSeekable();
   }
 
   @Override
   public boolean isPlayingAd() {
+    verifyApplicationThread();
     return player.isPlayingAd();
   }
 
   @Override
   public int getCurrentAdGroupIndex() {
+    verifyApplicationThread();
     return player.getCurrentAdGroupIndex();
   }
 
   @Override
   public int getCurrentAdIndexInAdGroup() {
+    verifyApplicationThread();
     return player.getCurrentAdIndexInAdGroup();
   }
 
   @Override
   public long getContentDuration() {
+    verifyApplicationThread();
     return player.getContentDuration();
   }
 
   @Override
   public long getContentPosition() {
+    verifyApplicationThread();
     return player.getContentPosition();
   }
 
   @Override
   public long getContentBufferedPosition() {
+    verifyApplicationThread();
     return player.getContentBufferedPosition();
   }
 
@@ -1183,12 +1248,23 @@ public class SimpleExoPlayer
 
   private void updatePlayWhenReady(
       boolean playWhenReady, @AudioFocusManager.PlayerCommand int playerCommand) {
-
     player.setPlayWhenReady(
         playWhenReady && playerCommand != AudioFocusManager.PLAYER_COMMAND_DO_NOT_PLAY,
         playerCommand != AudioFocusManager.PLAYER_COMMAND_PLAY_WHEN_READY);
   }
 
+  private void verifyApplicationThread() {
+    if (Looper.myLooper() != getApplicationLooper()) {
+      Log.w(
+          TAG,
+          "Player is accessed on the wrong thread. See "
+              + "https://google.github.io/ExoPlayer/faqs.html#"
+              + "what-do-player-is-accessed-on-the-wrong-thread-warnings-mean",
+          hasNotifiedFullWrongThreadWarning ? null : new IllegalStateException());
+      hasNotifiedFullWrongThreadWarning = true;
+    }
+  }
+
   private final class ComponentListener
       implements VideoRendererEventListener,
           AudioRendererEventListener,