improve SF logging/debugging a little bit

Change-Id: I6a57f89c25defc293fd748cc1fbd710031c02ec2
diff --git a/libs/surfaceflinger/LayerBase.h b/libs/surfaceflinger/LayerBase.h
index 7ac8bc5..852b9f9 100644
--- a/libs/surfaceflinger/LayerBase.h
+++ b/libs/surfaceflinger/LayerBase.h
@@ -369,6 +369,9 @@
 
     friend class Surface;
 
+protected:
+    mutable     bool            mDebug;
+
 private:
                 int32_t         mIndex;
     mutable     Mutex           mLock;