Add hints for potential overlay promotion on android.

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 09d380b82a9227b13bd343f91c3234ce00dc74bf..401dd547d19372c700ff011256fa0527e89ab870 100644
--- a/cc/output/overlay_candidate_validator.h
+++ b/cc/output/overlay_candidate_validator.h
@@ -8,11 +8,15 @@
 #include <vector>
 
 #include "cc/base/cc_export.h"
+#include "cc/base/resource_id.h"
 #include "cc/output/overlay_candidate.h"
 #include "cc/output/overlay_processor.h"
 
 namespace cc {
 
+class ResourceProvider;
+class RenderPass;
+
 // This class that can be used to answer questions about possible overlay
 // configurations for a particular output device.
 class CC_EXPORT OverlayCandidateValidator {
@@ -31,6 +35,13 @@ class CC_EXPORT OverlayCandidateValidator {
   // coordinates if necessary.
   virtual void CheckOverlaySupport(OverlayCandidateList* surfaces) = 0;
 
+  // Called before beginning a new pass for overlay promotion to clear out any
+  // promotable resources.  One must CheckoverlaySupport() again.
+  virtual void ClearPromotableResources() {}
+
+  // Returns whether |resource_id| is promotable.
+  virtual bool IsResourcePromotable(ResourceId resource_id);
+
   virtual ~OverlayCandidateValidator() {}
 };