Mac Overlays: Add sandwich strategy

content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc

Index: content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
diff --git a/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc b/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
index 60dc77852cb16fc7ff95be2732b6d6102431fcfd..964599b4d418a6db855913daaf16bff2b2ac0fdf 100644
--- a/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
+++ b/content/browser/compositor/gpu_surfaceless_browser_compositor_output_surface.cc
@@ -56,6 +56,11 @@ GpuSurfacelessBrowserCompositorOutputSurface::
     ~GpuSurfacelessBrowserCompositorOutputSurface() {
 }
 
+unsigned GpuSurfacelessBrowserCompositorOutputSurface::GetOverlayTextureId()
+    const {
+  return output_surface_->current_texture_id();
+}
+
 void GpuSurfacelessBrowserCompositorOutputSurface::SwapBuffers(
     cc::CompositorFrame* frame) {
   DCHECK(output_surface_);