Move AudioTrack.SESSION_ID_NOT_SET to C

It's a nicer place for it to live once it starts being passed
around more widely (e.g. through the video renderer, for
tunneling)

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=142158460

library/src/main/java/com/google/android/exoplayer2/C.java

@@ -97,6 +97,13 @@ public final class C {
   public static final int CRYPTO_MODE_AES_CBC = MediaCodec.CRYPTO_MODE_AES_CBC;
 
   /**
+   * Represents an unset {@link android.media.AudioTrack} session identifier. Equal to
+   * {@link AudioManager#AUDIO_SESSION_ID_GENERATE}.
+   */
+  @SuppressWarnings("InlinedApi")
+  public static final int AUDIO_SESSION_ID_UNSET = AudioManager.AUDIO_SESSION_ID_GENERATE;
+
+  /**
    * Represents an audio encoding, or an invalid or unset value.
    */
   @Retention(RetentionPolicy.SOURCE)

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

@@ -29,7 +29,6 @@ import android.view.SurfaceView;
 import android.view.TextureView;
 import com.google.android.exoplayer2.audio.AudioCapabilities;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
-import com.google.android.exoplayer2.audio.AudioTrack;
 import com.google.android.exoplayer2.audio.MediaCodecAudioRenderer;
 import com.google.android.exoplayer2.decoder.DecoderCounters;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
@@ -178,7 +177,7 @@ public class SimpleExoPlayer implements ExoPlayer {
 
     // Set initial values.
     audioVolume = 1;
-    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+    audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     audioStreamType = C.STREAM_TYPE_DEFAULT;
     videoScalingMode = C.VIDEO_SCALING_MODE_DEFAULT;
 
@@ -393,7 +392,7 @@ public class SimpleExoPlayer implements ExoPlayer {
   }
 
   /**
-   * Returns the audio session identifier, or {@code AudioTrack.SESSION_ID_NOT_SET} if not set.
+   * Returns the audio session identifier, or {@link C#AUDIO_SESSION_ID_UNSET} if not set.
    */
   public int getAudioSessionId() {
     return audioSessionId;
@@ -949,7 +948,7 @@ public class SimpleExoPlayer implements ExoPlayer {
       }
       audioFormat = null;
       audioDecoderCounters = null;
-      audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+      audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     }
 
     // TextRenderer.Output implementation

library/src/main/java/com/google/android/exoplayer2/audio/AudioTrack.java

@@ -19,7 +19,6 @@ import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.media.AudioAttributes;
 import android.media.AudioFormat;
-import android.media.AudioManager;
 import android.media.AudioTimestamp;
 import android.media.PlaybackParams;
 import android.os.ConditionVariable;
@@ -148,13 +147,6 @@ public final class AudioTrack {
   public static final int RESULT_BUFFER_CONSUMED = 2;
 
   /**
-   * Represents an unset {@link android.media.AudioTrack} session identifier. Equal to
-   * {@link AudioManager#AUDIO_SESSION_ID_GENERATE}.
-   */
-  @SuppressWarnings("InlinedApi")
-  public static final int SESSION_ID_NOT_SET = AudioManager.AUDIO_SESSION_ID_GENERATE;
-
-  /**
    * Returned by {@link #getCurrentPositionUs} when the position is not set.
    */
   public static final long CURRENT_POSITION_NOT_SET = Long.MIN_VALUE;
@@ -508,7 +500,8 @@ public final class AudioTrack {
   /**
    * Initializes the audio track for writing new buffers using {@link #handleBuffer}.
    *
-   * @param sessionId Audio track session identifier, or {@link #SESSION_ID_NOT_SET} to create one.
+   * @param sessionId Audio track session identifier, or {@link C#AUDIO_SESSION_ID_UNSET} to create
+   *     one.
    * @return The audio track session identifier.
    */
   public int initialize(int sessionId) throws InitializationException {
@@ -518,7 +511,8 @@ public final class AudioTrack {
   /**
    * Initializes the audio track for writing new buffers using {@link #handleBuffer}.
    *
-   * @param sessionId Audio track session identifier, or {@link #SESSION_ID_NOT_SET} to create one.
+   * @param sessionId Audio track session identifier, or {@link C#AUDIO_SESSION_ID_UNSET} to create
+   *     one.
    * @param tunneling Whether the audio track is to be used with tunneling video playback.
    * @return The audio track session identifier.
    */
@@ -539,7 +533,7 @@ public final class AudioTrack {
     if (useHwAvSync) {
       audioTrack = createHwAvSyncAudioTrackV21(sampleRate, channelConfig, targetEncoding,
           bufferSize, sessionId);
-    } else if (sessionId == SESSION_ID_NOT_SET) {
+    } else if (sessionId == C.AUDIO_SESSION_ID_UNSET) {
       audioTrack = new android.media.AudioTrack(streamType, sampleRate, channelConfig,
           targetEncoding, bufferSize, MODE_STREAM);
     } else {

library/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java

@@ -129,7 +129,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
       boolean playClearSamplesWithoutKeys, Handler eventHandler,
       AudioRendererEventListener eventListener, AudioCapabilities audioCapabilities) {
     super(C.TRACK_TYPE_AUDIO, mediaCodecSelector, drmSessionManager, playClearSamplesWithoutKeys);
-    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+    audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     audioTrack = new AudioTrack(audioCapabilities, this);
     eventDispatcher = new EventDispatcher(eventHandler, eventListener);
   }
@@ -274,7 +274,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
 
   @Override
   protected void onDisabled() {
-    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+    audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     try {
       audioTrack.release();
     } finally {
@@ -328,8 +328,8 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
     if (!audioTrack.isInitialized()) {
       // Initialize the AudioTrack now.
       try {
-        if (audioSessionId == AudioTrack.SESSION_ID_NOT_SET) {
-          audioSessionId = audioTrack.initialize(AudioTrack.SESSION_ID_NOT_SET);
+        if (audioSessionId == C.AUDIO_SESSION_ID_UNSET) {
+          audioSessionId = audioTrack.initialize(C.AUDIO_SESSION_ID_UNSET);
           eventDispatcher.audioSessionId(audioSessionId);
           onAudioSessionId(audioSessionId);
         } else {
@@ -387,7 +387,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
       case C.MSG_SET_STREAM_TYPE:
         @C.StreamType int streamType = (Integer) message;
         if (audioTrack.setStreamType(streamType)) {
-          audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+          audioSessionId = C.AUDIO_SESSION_ID_UNSET;
         }
         break;
       default:

library/src/main/java/com/google/android/exoplayer2/audio/SimpleDecoderAudioRenderer.java

@@ -145,7 +145,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
     this.drmSessionManager = drmSessionManager;
     formatHolder = new FormatHolder();
     this.playClearSamplesWithoutKeys = playClearSamplesWithoutKeys;
-    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+    audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     decoderReinitializationState = REINITIALIZATION_STATE_NONE;
     audioTrackNeedsConfigure = true;
   }
@@ -245,8 +245,8 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
     }
 
     if (!audioTrack.isInitialized()) {
-      if (audioSessionId == AudioTrack.SESSION_ID_NOT_SET) {
-        audioSessionId = audioTrack.initialize(AudioTrack.SESSION_ID_NOT_SET);
+      if (audioSessionId == C.AUDIO_SESSION_ID_UNSET) {
+        audioSessionId = audioTrack.initialize(C.AUDIO_SESSION_ID_UNSET);
         eventDispatcher.audioSessionId(audioSessionId);
         onAudioSessionId(audioSessionId);
       } else {
@@ -425,7 +425,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
   @Override
   protected void onDisabled() {
     inputFormat = null;
-    audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+    audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     audioTrackNeedsConfigure = true;
     waitingForKeys = false;
     try {
@@ -554,7 +554,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
       case C.MSG_SET_STREAM_TYPE:
         @C.StreamType int streamType = (Integer) message;
         if (audioTrack.setStreamType(streamType)) {
-          audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
+          audioSessionId = C.AUDIO_SESSION_ID_UNSET;
         }
         break;
       default: