Explicitly document internal onXError are for reporting only

Issue: #3366

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=174214690

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

@@ -24,6 +24,7 @@ import android.support.annotation.IntDef;
 import android.support.annotation.NonNull;
 import android.text.TextUtils;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.drm.DefaultDrmSession.ProvisioningManager;
 import com.google.android.exoplayer2.drm.DrmInitData.SchemeData;
 import com.google.android.exoplayer2.drm.DrmSession.DrmSessionException;
@@ -58,6 +59,13 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto> implements DrmSe
 
     /**
      * Called when a drm error occurs.
+     * <p>
+     * This method being called does not indicate that playback has failed, or that it will fail.
+     * The player may be able to recover from the error and continue. Hence applications should
+     * <em>not</em> implement this method to display a user visible error or initiate an application
+     * level retry ({@link Player.EventListener#onPlayerError} is the appropriate place to implement
+     * such behavior). This method is called to provide the application with an opportunity to log
+     * the error if it wishes to do so.
      *
      * @param e The corresponding exception.
      */

library/core/src/main/java/com/google/android/exoplayer2/source/AdaptiveMediaSourceEventListener.java

@@ -19,6 +19,7 @@ import android.os.Handler;
 import android.os.SystemClock;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.IOException;
@@ -111,6 +112,13 @@ public interface AdaptiveMediaSourceEventListener {
    * The error may or may not have resulted in the load being canceled, as indicated by the
    * {@code wasCanceled} parameter. If the load was canceled, {@link #onLoadCanceled} will
    * <em>not</em> be called in addition to this method.
+   * <p>
+   * This method being called does not indicate that playback has failed, or that it will fail. The
+   * player may be able to recover from the error and continue. Hence applications should
+   * <em>not</em> implement this method to display a user visible error or initiate an application
+   * level retry ({@link Player.EventListener#onPlayerError} is the appropriate place to implement
+   * such behavior). This method is called to provide the application with an opportunity to log the
+   * error if it wishes to do so.
    *
    * @param dataSpec Defines the data being loaded.
    * @param dataType One of the {@link C} {@code DATA_TYPE_*} constants defining the type of data

library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java

@@ -19,6 +19,7 @@ import android.net.Uri;
 import android.os.Handler;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayer;
+import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.extractor.DefaultExtractorsFactory;
 import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorsFactory;
@@ -47,6 +48,13 @@ public final class ExtractorMediaSource implements MediaSource, ExtractorMediaPe
 
     /**
      * Called when an error occurs loading media data.
+     * <p>
+     * This method being called does not indicate that playback has failed, or that it will fail.
+     * The player may be able to recover from the error and continue. Hence applications should
+     * <em>not</em> implement this method to display a user visible error or initiate an application
+     * level retry ({@link Player.EventListener#onPlayerError} is the appropriate place to implement
+     * such behavior). This method is called to provide the application with an opportunity to log
+     * the error if it wishes to do so.
      *
      * @param error The load error.
      */