Revert "Revert "fix [2793164] Spam 2x/second with TOT master in SurfaceFlinger""

This reverts commit 330dd304a471d260a73e342a240921c03c825f99.
diff --git a/libs/surfaceflinger/LayerBuffer.h b/libs/surfaceflinger/LayerBuffer.h
index 413b8a4..1c0bf83 100644
--- a/libs/surfaceflinger/LayerBuffer.h
+++ b/libs/surfaceflinger/LayerBuffer.h
@@ -47,6 +47,7 @@
         virtual void postBuffer(ssize_t offset);
         virtual void unregisterBuffers();
         virtual void destroy() { }
+        SurfaceFlinger* getFlinger() const { return mLayer.mFlinger.get(); }
     protected:
         LayerBuffer& mLayer;
     };