Fix DXGIYCbCrTextureHost not setting a TextureSourceProvider. (bug 1350251, r=mattwoodrow)

--HG--
extra : rebase_source : e6426ddb660ab2df6f263ff01a959deab86d60ce

gfx/layers/d3d11/TextureD3D11.cpp

@@ -895,12 +895,15 @@ void
 DXGIYCbCrTextureHostD3D11::SetTextureSourceProvider(TextureSourceProvider* aProvider)
 {
   if (!aProvider || !aProvider->GetD3D11Device()) {
+    mProvider = nullptr;
     mTextureSources[0] = nullptr;
     mTextureSources[1] = nullptr;
     mTextureSources[2] = nullptr;
     return;
   }
 
+  mProvider = aProvider;
+
   if (mTextureSources[0]) {
     mTextureSources[0]->SetTextureSourceProvider(aProvider);
   }