DNR Prototype: With flatbuffers

extensions/browser/app_window/BUILD.gn

Index: extensions/browser/app_window/BUILD.gn
diff --git a/extensions/browser/app_window/BUILD.gn b/extensions/browser/app_window/BUILD.gn
index d903645c23152588ad03ebb755b09cb2987979e0..c6ce4f89558629f60a92e0db753f7b1748e07f47 100644
--- a/extensions/browser/app_window/BUILD.gn
+++ b/extensions/browser/app_window/BUILD.gn
@@ -32,4 +32,9 @@ source_set("app_window") {
     "//extensions:extensions_browser_resources",
     "//extensions/strings",
   ]
+
+  # This is because app_window depends on extensions/browser w/o declaring a
+  # dependency. See gn check out/Default extensions/browser/app_window will
+  # fail.
+  include_dirs = [ "//third_party/flatbuffers/src/include/" ]
 }