Consolidate OutputSurface constructors into GL vs Vulkan.

cc/output/overlay_unittest.cc

Index: cc/output/overlay_unittest.cc
diff --git a/cc/output/overlay_unittest.cc b/cc/output/overlay_unittest.cc
index b95d46c7801a5092745564c22df85579dda1a6da..b9f4a719333e0243cfc87d45ea33c84a0c26ae68 100644
--- a/cc/output/overlay_unittest.cc
+++ b/cc/output/overlay_unittest.cc
@@ -134,7 +134,7 @@ size_t DefaultOverlayProcessor::GetStrategyCount() {
 class OverlayOutputSurface : public OutputSurface {
  public:
   explicit OverlayOutputSurface(scoped_refptr<ContextProvider> context_provider)
-      : OutputSurface(context_provider) {
+      : OutputSurface(context_provider, nullptr, nullptr) {
     surface_size_ = kDisplaySize;
     device_scale_factor_ = 1;
     is_displayed_as_overlay_plane_ = true;