Mac Overlays: Add sandwich strategy

cc/output/overlay_strategy_single_on_top.h

Index: cc/output/overlay_strategy_single_on_top.h
diff --git a/cc/output/overlay_strategy_single_on_top.h b/cc/output/overlay_strategy_single_on_top.h
index 2b9cf4d04fddcb80e619c12b9ab0f8656e193675..a082e9391ac81c9545b7ed98c3bcb6528f1eb2a4 100644
--- a/cc/output/overlay_strategy_single_on_top.h
+++ b/cc/output/overlay_strategy_single_on_top.h
@@ -17,15 +17,18 @@ namespace cc {
 class StreamVideoDrawQuad;
 class TextureDrawQuad;
 
-class CC_EXPORT OverlayStrategySingleOnTop : public OverlayStrategyCommon {
+class CC_EXPORT OverlayStrategySingleOnTop
+    : public OverlayStrategyCommonDelegate {
  public:
-  explicit OverlayStrategySingleOnTop(
-      OverlayCandidateValidator* capability_checker);
+  OverlayStrategySingleOnTop() {}
+  ~OverlayStrategySingleOnTop() override;
+
   bool TryOverlay(OverlayCandidateValidator* capability_checker,
                   RenderPassList* render_passes_in_draw_order,
                   OverlayCandidateList* candidate_list,
                   const OverlayCandidate& candidate,
-                  QuadList::Iterator candidate_iterator) override;
+                  QuadList::Iterator candidate_iterator,
+                  float device_scale_factor) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(OverlayStrategySingleOnTop);