--- a/dom/media/platforms/wmf/DXVA2Manager.cpp
+++ b/dom/media/platforms/wmf/DXVA2Manager.cpp
@@ -154,17 +154,16 @@ private:
   RefPtr<IDirect3DDevice9Ex> mDevice;
   RefPtr<IDirect3DDeviceManager9> mDeviceManager;
   RefPtr<D3D9RecycleAllocator> mTextureClientAllocator;
   RefPtr<IDirectXVideoDecoderService> mDecoderService;
   RefPtr<IDirect3DSurface9> mSyncSurface;
   RefPtr<IDirectXVideoDecoder> mDecoder;
   GUID mDecoderGUID;
   UINT32 mResetToken = 0;
-  bool mFirstFrame = true;
 };
 
 void GetDXVA2ExtendedFormatFromMFMediaType(IMFMediaType *pType,
                                            DXVA2_ExtendedFormat *pFormat)
 {
   // Get the interlace mode.
   MFVideoInterlaceMode interlace = MFVideoInterlaceMode(MFGetAttributeUINT32(
     pType, MF_MT_INTERLACE_MODE, MFVideoInterlace_Unknown));