athena: Use mojo to provide the bindings for the virtual keyboard.

ui/keyboard/BUILD.gn

Index: ui/keyboard/BUILD.gn
diff --git a/ui/keyboard/BUILD.gn b/ui/keyboard/BUILD.gn
index 8c1c2a2511eb4be9022bde52b9027d06a2c959b3..8321077d0c04077b3fe7e7bb6b173427c12ef3a4 100644
--- a/ui/keyboard/BUILD.gn
+++ b/ui/keyboard/BUILD.gn
@@ -52,6 +52,16 @@ grit("resources_grit") {
     "keyboard_resources.pak",
     "keyboard_resources.rc",
   ]
+
+  keyboard_mojom_gen_js = "$root_gen_dir/ui/keyboard/webui/keyboard.mojom.js"
+  grit_flags = [
+    "-E", "keyboard_mojom_gen_js=" +
+          rebase_path(keyboard_mojom_gen_js, root_build_dir),
+  ]
+
+  deps = [
+    "webui:mojo_bindings"
+  ]
 }
 
 copy("resources") {