Add a full screen virtual keyboard to virtual keyboard root window

ui/keyboard/keyboard_util.cc

Index: ui/keyboard/keyboard_util.cc
diff --git a/ui/keyboard/keyboard_util.cc b/ui/keyboard/keyboard_util.cc
index 96d8385a05fddfe53103522b90eb99c21a340ae1..636004daaf34aa78150dcb72e1ddf6e1da65d11a 100644
--- a/ui/keyboard/keyboard_util.cc
+++ b/ui/keyboard/keyboard_util.cc
@@ -47,6 +47,11 @@ bool IsKeyboardEnabled() {
 
 }
 
+bool IsKeyboardUsabilityTestEnabled() {
+  return CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kKeyboardUsabilityTest);
+}
+
 bool InsertText(const base::string16& text, aura::Window* root_window) {
   if (!root_window)
     return false;