media: AVDA now doesn't queue EOS for a flush if the codec is empty

media/gpu/android_video_decode_accelerator.h

Index: media/gpu/android_video_decode_accelerator.h
diff --git a/media/gpu/android_video_decode_accelerator.h b/media/gpu/android_video_decode_accelerator.h
index 335b3676a5ba8b97f75d7b782dfb9ac43827342d..a32841e7ff2efe65e94cecb6148ed3345fbccb71 100644
--- a/media/gpu/android_video_decode_accelerator.h
+++ b/media/gpu/android_video_decode_accelerator.h
@@ -94,7 +94,6 @@ class MEDIA_GPU_EXPORT AndroidVideoDecodeAccelerator
   };
 
   enum DrainType {
-    DRAIN_TYPE_NONE,
     DRAIN_FOR_FLUSH,
     DRAIN_FOR_RESET,
     DRAIN_FOR_DESTROY,
@@ -282,9 +281,8 @@ class MEDIA_GPU_EXPORT AndroidVideoDecodeAccelerator
   // Time at which we last did useful work on io_timer_.
   base::TimeTicks most_recent_work_;
 
-  // Type of a drain request. We need to distinguish between DRAIN_FOR_FLUSH
-  // and other types, see IsDrainingForResetOrDestroy().
-  DrainType drain_type_;
+  // The ongoing drain operation, if any.
+  base::Optional<DrainType> drain_type_;
 
   // Holds a ref-count to the CDM to avoid using the CDM after it's destroyed.
   scoped_refptr<MediaKeys> cdm_for_reference_holding_only_;