Force U.S. English keyboard layout for TextfieldTest.KeysWithModifiersTest

ui/events/BUILD.gn

Index: ui/events/BUILD.gn
diff --git a/ui/events/BUILD.gn b/ui/events/BUILD.gn
index dd9c9ff36daf25394aa5ea2dd52ac752f0f9244b..34983b0e9c96676eb4e358049460b666b1a9d40d 100644
--- a/ui/events/BUILD.gn
+++ b/ui/events/BUILD.gn
@@ -276,6 +276,10 @@ static_library("test_support") {
     "test/event_generator.h",
     "test/events_test_utils.cc",
     "test/events_test_utils.h",
+    "test/keyboard_layout.cc",
+    "test/keyboard_layout.h",
+    "test/keyboard_layout_mac.cc",
+    "test/keyboard_layout_win.cc",
     "test/motion_event_test_utils.cc",
     "test/motion_event_test_utils.h",
     "test/platform_event_source_test_api.cc",