Mac Overlays: Allow multiple overlays with sandwich strategy

cc/output/overlay_strategy_underlay.cc

Index: cc/output/overlay_strategy_underlay.cc
diff --git a/cc/output/overlay_strategy_underlay.cc b/cc/output/overlay_strategy_underlay.cc
index 67cd77d4cd1f2b75f60a7049c259587e1a1b7634..3aa10860e992154fc434b0122a91a5de5a3a6e3d 100644
--- a/cc/output/overlay_strategy_underlay.cc
+++ b/cc/output/overlay_strategy_underlay.cc
@@ -12,7 +12,7 @@ namespace cc {
 
 OverlayStrategyUnderlay::~OverlayStrategyUnderlay() {}
 
-bool OverlayStrategyUnderlay::TryOverlay(
+QuadList::Iterator OverlayStrategyUnderlay::TryOverlay(
     OverlayCandidateValidator* capability_checker,
     RenderPassList* render_passes_in_draw_order,
     OverlayCandidateList* candidate_list,
@@ -46,10 +46,11 @@ bool OverlayStrategyUnderlay::TryOverlay(
             candidate_iterator);
     replacement->SetAll(shared_quad_state, rect, rect, rect, false,
                         SK_ColorTRANSPARENT, true);
+    DCHECK(candidate_list->empty());
     candidate_list->swap(candidates);

[ccameron, 2015/09/02 22:22:33]

same issue about return values here.

-    return true;
   }
-  return false;
+
+  return quad_list.end();
 }
 
 }  // namespace cc