Don't advertise support for video/mpeg ads

Issue: #4297

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=198536888

RELEASENOTES.md

@@ -4,6 +4,8 @@
 
 * Fix inconsistent `Player.EventListener` invocations for recursive player state
   changes ([#4276](https://github.com/google/ExoPlayer/issues/4276)).
+* IMA: Don't advertise support for video/mpeg ad media, as we don't have an
+  extractor for this ([#4297](https://github.com/google/ExoPlayer/issues/4297)).
 
 ### 2.8.1 ###
 

extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsLoader.java

@@ -447,9 +447,13 @@ public final class ImaAdsLoader extends Player.DefaultEventListener implements A
       } else if (contentType == C.TYPE_HLS) {
         supportedMimeTypes.add(MimeTypes.APPLICATION_M3U8);
       } else if (contentType == C.TYPE_OTHER) {
-        supportedMimeTypes.addAll(Arrays.asList(
-            MimeTypes.VIDEO_MP4, MimeTypes.VIDEO_WEBM, MimeTypes.VIDEO_H263, MimeTypes.VIDEO_MPEG,
-            MimeTypes.AUDIO_MP4, MimeTypes.AUDIO_MPEG));
+        supportedMimeTypes.addAll(
+            Arrays.asList(
+                MimeTypes.VIDEO_MP4,
+                MimeTypes.VIDEO_WEBM,
+                MimeTypes.VIDEO_H263,
+                MimeTypes.AUDIO_MP4,
+                MimeTypes.AUDIO_MPEG));
       } else if (contentType == C.TYPE_SS) {
         // IMA does not support Smooth Streaming ad media.
       }