Add --keyboard-usability-test flag and always show keyboard unless manually hide

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 8b0d817b990eb1645e14d2a51b7cba90dd6411a1..14e156a5f83524ac35ff51c5e76a291594d43879 100644
--- a/ui/keyboard/keyboard_util.cc
+++ b/ui/keyboard/keyboard_util.cc
@@ -36,7 +36,10 @@ namespace keyboard {
 
 bool IsKeyboardEnabled() {
   return CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableVirtualKeyboard);
+      switches::kEnableVirtualKeyboard) ||
+          CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kKeyboardUsabilityTest);
+
 }
 
 bool InsertText(const base::string16& text, aura::RootWindow* root_window) {