Clarify DRM error deferral comments

- I don't think the session recovering later would work, because
  the codec will be configured not to use it.
- I'm not sure session recovery makes sense in general, and our
  implementations do not do this. Document it as a terminal state
  for now.

PiperOrigin-RevId: 340204194

library/core/src/main/java/com/google/android/exoplayer2/audio/DecoderAudioRenderer.java

@@ -603,8 +603,8 @@ public abstract class DecoderAudioRenderer<
       if (mediaCrypto == null) {
         DrmSessionException drmError = decoderDrmSession.getError();
         if (drmError != null) {
-          // Continue for now. We may be able to avoid failure if the session recovers, or if a new
-          // input format causes the session to be replaced before it's used.
+          // Continue for now. We may be able to avoid failure if a new input format causes the
+          // session to be replaced without it having been used.
         } else {
           // The drm session isn't open yet.
           return;

library/core/src/main/java/com/google/android/exoplayer2/drm/DrmSession.java

@@ -66,12 +66,11 @@ public interface DrmSession {
   @Retention(RetentionPolicy.SOURCE)
   @IntDef({STATE_RELEASED, STATE_ERROR, STATE_OPENING, STATE_OPENED, STATE_OPENED_WITH_KEYS})
   @interface State {}
-  /**
-   * The session has been released.
-   */
+  /** The session has been released. This is a terminal state. */
   int STATE_RELEASED = 0;
   /**
    * The session has encountered an error. {@link #getError()} can be used to retrieve the cause.
+   * This is a terminal state.
    */
   int STATE_ERROR = 1;
   /**

library/core/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecRenderer.java

@@ -499,8 +499,8 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
         if (sessionMediaCrypto == null) {
           @Nullable DrmSessionException drmError = codecDrmSession.getError();
           if (drmError != null) {
-            // Continue for now. We may be able to avoid failure if the session recovers, or if a
-            // new input format causes the session to be replaced before it's used.
+            // Continue for now. We may be able to avoid failure if a new input format causes the
+            // session to be replaced without it having been used.
           } else {
             // The drm session isn't open yet.
             return;

library/core/src/main/java/com/google/android/exoplayer2/video/DecoderVideoRenderer.java

@@ -661,8 +661,8 @@ public abstract class DecoderVideoRenderer extends BaseRenderer {
       if (mediaCrypto == null) {
         DrmSessionException drmError = decoderDrmSession.getError();
         if (drmError != null) {
-          // Continue for now. We may be able to avoid failure if the session recovers, or if a new
-          // input format causes the session to be replaced before it's used.
+          // Continue for now. We may be able to avoid failure if a new input format causes the
+          // session to be replaced without it having been used.
         } else {
           // The drm session isn't open yet.
           return;