Add missing onLoadStarted events to HLS playlist tracker.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=200211755

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

@@ -96,7 +96,10 @@ public final class DefaultHlsPlaylistTracker
             initialPlaylistUri,
             initialPlaylistUri,
             C.DATA_TYPE_MANIFEST,
             C.DATA_TYPE_MANIFEST,
             playlistParser);
             playlistParser);
-    initialPlaylistLoader.startLoading(masterPlaylistLoadable, this, minRetryCount);
+    long elapsedRealtime =
+        initialPlaylistLoader.startLoading(masterPlaylistLoadable, this, minRetryCount);
+    eventDispatcher.loadStarted(
+        masterPlaylistLoadable.dataSpec, masterPlaylistLoadable.type, elapsedRealtime);
   }
   }
 
 
   @Override
   @Override
@@ -509,7 +512,10 @@ public final class DefaultHlsPlaylistTracker
     // Internal methods.
     // Internal methods.
 
 
     private void loadPlaylistImmediately() {
     private void loadPlaylistImmediately() {
-      mediaPlaylistLoader.startLoading(mediaPlaylistLoadable, this, minRetryCount);
+      long elapsedRealtime =
+          mediaPlaylistLoader.startLoading(mediaPlaylistLoadable, this, minRetryCount);
+      eventDispatcher.loadStarted(
+          mediaPlaylistLoadable.dataSpec, mediaPlaylistLoadable.type, elapsedRealtime);
     }
     }
 
 
     private void processLoadedPlaylist(HlsMediaPlaylist loadedPlaylist) {
     private void processLoadedPlaylist(HlsMediaPlaylist loadedPlaylist) {