Update transactions.proto to sync with layer_state_t

I92ed7c4fdf09a2133efda4172e2f61f4a198e51b added
eLayerIsDisplayDecoration to layer_state_t. Update LayerState to match.

Bug: 193170859
Test: NA
Change-Id: Ib8e17c71bd1fdd97b881df4251b1b53d33a144e4
diff --git a/services/surfaceflinger/layerproto/transactions.proto b/services/surfaceflinger/layerproto/transactions.proto
index e31b502..3cb1076 100644
--- a/services/surfaceflinger/layerproto/transactions.proto
+++ b/services/surfaceflinger/layerproto/transactions.proto
@@ -139,6 +139,7 @@
         eLayerSkipScreenshot = 0x40;
         eLayerSecure = 0x80;
         eEnableBackpressure = 0x100;
+        eLayerIsDisplayDecoration = 0x200;
     };
     uint32 flags = 9;
     uint32 mask = 10;