[flutter_conductor] implement UI scaffold (#90621)

https://dart.googlesource.com/external/github.com/flutter/flutter/+/69ae50310b07f8ef80fd1f14af8209adb2b83f03
diff --git a/commits.json b/commits.json
index 610e9cd..b227e31 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "external/github.com/flutter/engine":"5f7d0053f98dd5284f69514504e8b0f318ac9f13",
-  "external/github.com/flutter/flutter":"08a30fdb92df1e6bbc078f43012f3278154f6c30",
+  "external/github.com/flutter/flutter":"69ae50310b07f8ef80fd1f14af8209adb2b83f03",
   "sdk":"70533ae7fa89c28dffe6ae1e693c124278ff6a34"
 }
\ No newline at end of file