Add hints for potential overlay promotion on android.

components/display_compositor/compositor_overlay_candidate_validator_android.h

Index: components/display_compositor/compositor_overlay_candidate_validator_android.h
diff --git a/components/display_compositor/compositor_overlay_candidate_validator_android.h b/components/display_compositor/compositor_overlay_candidate_validator_android.h
index 0dd3becf66b4339ab72b14e7badd4d5e9b8d7944..fde5f844be92a716c860d08168f8830a3bece9db 100644
--- a/components/display_compositor/compositor_overlay_candidate_validator_android.h
+++ b/components/display_compositor/compositor_overlay_candidate_validator_android.h
@@ -5,10 +5,19 @@
 #ifndef COMPONENTS_DISPLAY_COMPOSITOR_COMPOSITOR_OVERLAY_CANDIDATE_VALIDATOR_ANDROID_H_
 #define COMPONENTS_DISPLAY_COMPOSITOR_COMPOSITOR_OVERLAY_CANDIDATE_VALIDATOR_ANDROID_H_
 
+#include <set>
+
 #include "base/macros.h"
 #include "components/display_compositor/compositor_overlay_candidate_validator.h"
 #include "components/display_compositor/display_compositor_export.h"
 
+namespace cc {
+class DrawQuad;
+class OverlayPromotabilityCallback;
+class ResourceProvider;
+class RenderPass;
+}
+
 namespace display_compositor {
 
 // An overlay validator for supporting fullscreen video underlays on Android.
@@ -31,7 +40,13 @@ class DISPLAY_COMPOSITOR_EXPORT CompositorOverlayCandidateValidatorAndroid
 
   void SetSoftwareMirrorMode(bool enabled) override;
 
+  void ClearPromotableResources() override;
+
+  bool IsResourcePromotable(cc::ResourceId resource_id) override;
+
  private:
+  std::set<cc::ResourceId> promotable_resources_;
+
   DISALLOW_COPY_AND_ASSIGN(CompositorOverlayCandidateValidatorAndroid);
 };