Fix HLS' mime type propagation

Issue:#3653

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182064250

RELEASENOTES.md

@@ -2,6 +2,8 @@
 
 ### dev-v2 (not yet released) ###
 
+* HLS: Fix mime type propagation
+  ([#3653](https://github.com/google/ExoPlayer/issues/3653)).
 * SimpleExoPlayerView: Automatically apply video rotation if
   `SimpleExoPlayerView` is configured to use `TextureView`
   ([#91](https://github.com/google/ExoPlayer/issues/91)).

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

@@ -474,8 +474,15 @@ public final class Format implements Parcelable {
         drmInitData, metadata);
   }
 
-  public Format copyWithContainerInfo(String id, String codecs, int bitrate, int width, int height,
-      @C.SelectionFlags int selectionFlags, String language) {
+  public Format copyWithContainerInfo(
+      String id,
+      String sampleMimeType,
+      String codecs,
+      int bitrate,
+      int width,
+      int height,
+      @C.SelectionFlags int selectionFlags,
+      String language) {
     return new Format(id, containerMimeType, sampleMimeType, codecs, bitrate, maxInputSize, width,
         height, frameRate, rotationDegrees, pixelWidthHeightRatio, projectionData, stereoMode,
         colorInfo, channelCount, sampleRate, pcmEncoding, encoderDelay, encoderPadding,

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsSampleStreamWrapper.java

@@ -882,8 +882,10 @@ import java.util.Arrays;
     int bitrate = propagateBitrate ? playlistFormat.bitrate : Format.NO_VALUE;
     int sampleTrackType = MimeTypes.getTrackType(sampleFormat.sampleMimeType);
     String codecs = Util.getCodecsOfType(playlistFormat.codecs, sampleTrackType);
+    String mimeType = MimeTypes.getMediaMimeType(codecs);
     return sampleFormat.copyWithContainerInfo(
         playlistFormat.id,
+        mimeType,
         codecs,
         bitrate,
         playlistFormat.width,