cc: Fork OverlayCandidate to CALayerOverlay

cc/output/overlay_candidate_validator.h

Index: cc/output/overlay_candidate_validator.h
diff --git a/cc/output/overlay_candidate_validator.h b/cc/output/overlay_candidate_validator.h
index 8586b4de1703d9f31b3bd4841fcc7ed73a2b8866..09d380b82a9227b13bd343f91c3234ce00dc74bf 100644
--- a/cc/output/overlay_candidate_validator.h
+++ b/cc/output/overlay_candidate_validator.h
@@ -20,6 +20,9 @@ class CC_EXPORT OverlayCandidateValidator {
   // Populates a list of strategies that may work with this validator.
   virtual void GetStrategies(OverlayProcessor::StrategyList* strategies) = 0;
 
+  // Returns true if draw quads can be represented as CALayers (Mac only).
+  virtual bool AllowCALayerOverlays() = 0;
+
   // A list of possible overlay candidates is presented to this function.
   // The expected result is that those candidates that can be in a separate
   // plane are marked with |overlay_handled| set to true, otherwise they are