Do not create AX tree for surface tree

These windows are just place holders for textures (+event handling)
and does not represent actual UI.

Bug: 1439686

Change-Id: Ifc1002b634cdb05e1c7243fc0d0251bd31ee4231
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4461392
Reviewed-by: Yuzhu Shen <[email protected]>
Commit-Queue: Mitsuru Oshima <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1137225}
diff --git a/components/exo/BUILD.gn b/components/exo/BUILD.gn
index 2a17910..5fba7eb 100644
--- a/components/exo/BUILD.gn
+++ b/components/exo/BUILD.gn
@@ -158,6 +158,7 @@
     "//services/viz/privileged/mojom/compositing",
     "//skia",
     "//third_party/blink/public/common",
+    "//ui/accessibility",
     "//ui/accessibility:ax_base",
     "//ui/aura",
     "//ui/base",