Allow resetting DXVAVDA while it's currently flushing.

media/gpu/dxva_video_decode_accelerator_win.cc

Index: media/gpu/dxva_video_decode_accelerator_win.cc
diff --git a/media/gpu/dxva_video_decode_accelerator_win.cc b/media/gpu/dxva_video_decode_accelerator_win.cc
index 5f730e80d3eb6b5b3283a39b97254d6afdef1398..a92b1dd5b559534480af4a960156fa5bab5b0f71 100644
--- a/media/gpu/dxva_video_decode_accelerator_win.cc
+++ b/media/gpu/dxva_video_decode_accelerator_win.cc
@@ -1001,12 +1001,15 @@ void DXVAVideoDecodeAccelerator::Reset() {
   DVLOG(1) << "DXVAVideoDecodeAccelerator::Reset";
 
   State state = GetState();
-  RETURN_AND_NOTIFY_ON_FAILURE((state == kNormal || state == kStopped),
-                               "Reset: invalid state: " << state,
-                               ILLEGAL_STATE, );
+  RETURN_AND_NOTIFY_ON_FAILURE(
+      (state == kNormal || state == kStopped || state == kFlushing),
+      "Reset: invalid state: " << state, ILLEGAL_STATE, );
 
   decoder_thread_.Stop();
 
+  if (state == kFlushing)
+    NotifyFlushDone();
+
   SetState(kResetting);
 
   // If we have pending output frames waiting for display then we drop those