Bug 1097441 - Use SetScaleToSize for scaling videos so that it works for asynchronous size changes. r=roc

--HG--
extra : rebase_source : c18b17e8b146aa8a7cebc4125fd0dc86fb20f882

layout/generic/nsVideoFrame.cpp

@@ -223,9 +223,8 @@ nsVideoFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
   // Set a transform on the layer to draw the video in the right place
   gfxPoint p = r.TopLeft() + aContainerParameters.mOffset;
   Matrix transform = Matrix::Translation(p.x, p.y);
-  transform.PreScale(r.Width() / frameSize.width,
-                     r.Height() / frameSize.height);
   layer->SetBaseTransform(gfx::Matrix4x4::From2D(transform));
+  layer->SetScaleToSize(IntSize(r.width, r.height), ScaleMode::STRETCH);
   nsRefPtr<Layer> result = layer.forget();
   return result.forget();
 }