[KeyboardEvent] Use DOM |code| rather than Windows-based key code

ui/events/event_unittest.cc

Index: ui/events/event_unittest.cc
diff --git a/ui/events/event_unittest.cc b/ui/events/event_unittest.cc
index 7e92aa0a9696b32c490e4dbbd30e9f0b8be5659a..45b470b984418d76dfc11b30626bccf3aa7d256e 100644
--- a/ui/events/event_unittest.cc
+++ b/ui/events/event_unittest.cc
@@ -351,11 +351,10 @@ TEST(EventTest, KeyEventCode) {
     EXPECT_EQ(kCodeForSpace, key.GetCodeString());
   }
   {
-    // If the synthetic event is initialized without code, it returns
-    // an empty string.
-    // TODO(komatsu): Fill a fallback value assuming the US keyboard layout.
+    // If the synthetic event is initialized without code, the code is
+    // determined based on the KeyboardCode using US keyboard layout.
     KeyEvent key(ET_KEY_PRESSED, VKEY_SPACE, EF_NONE);
-    EXPECT_TRUE(key.GetCodeString().empty());
+    EXPECT_EQ(kCodeForSpace, key.GetCodeString());
   }
 #if defined(USE_X11)
   {