SkImage method for detecting lazy decoding

src/lazy/SkDiscardablePixelRef.h

Index: src/lazy/SkDiscardablePixelRef.h
diff --git a/src/lazy/SkDiscardablePixelRef.h b/src/lazy/SkDiscardablePixelRef.h
index e8451ee26905de6bd3cfb276b5a1ad4fb0dd4070..3b38fa669c9c27d0e863354df6aec4222f52c711 100644
--- a/src/lazy/SkDiscardablePixelRef.h
+++ b/src/lazy/SkDiscardablePixelRef.h
@@ -36,6 +36,8 @@ protected:
         return fGenerator->refEncodedData();
     }
 
+    bool onIsLazyGenerated() const override { return true; }
+
 private:
     SkImageGenerator* const fGenerator;
     SkDiscardableMemory::Factory* const fDMFactory;