Don't exclude Windows when instantiating SkiaOutputSurfaceImpl

SkiaRenderer already works on Windows when direct composition is
disabled (with some minor quirks during resize) so don't automatically
fail to create an output surface on Windows.

Change-Id: I420d8a288c1e11d1f68ef9f339019545a35f2aff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1594833Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656463}

components/viz/service/display_embedder/output_surface_provider_impl.cc

@@ -105,7 +105,7 @@ std::unique_ptr<OutputSurface> OutputSurfaceProviderImpl::CreateOutputSurface(
         CreateSoftwareOutputDeviceForPlatform(surface_handle, display_client));
   } else if (renderer_settings.use_skia_renderer ||
              renderer_settings.use_skia_renderer_non_ddl) {
-#if defined(OS_MACOSX) || defined(OS_WIN)
+#if defined(OS_MACOSX)
     // TODO(penghuang): Support SkiaRenderer for all platforms.
     NOTIMPLEMENTED();
     return nullptr;