cros: Allow JS to control virtual keyboard on sign-in screen.

ui/keyboard/keyboard_controller.cc

Index: ui/keyboard/keyboard_controller.cc
diff --git a/ui/keyboard/keyboard_controller.cc b/ui/keyboard/keyboard_controller.cc
index e0912a72d1b8c9fdec50c2ded0d21086bd688b3e..99382355071522537e16a2da2d52d7ee146b841b 100644
--- a/ui/keyboard/keyboard_controller.cc
+++ b/ui/keyboard/keyboard_controller.cc
@@ -274,6 +274,10 @@ void KeyboardController::AddObserver(KeyboardControllerObserver* observer) {
   observer_list_.AddObserver(observer);
 }
 
+bool KeyboardController::HasObserver(KeyboardControllerObserver* observer) {
+  return observer_list_.HasObserver(observer);
+}
+
 void KeyboardController::RemoveObserver(KeyboardControllerObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }