Revert of chromeos: Remove some IME methods from ash::SystemTrayDelegate

ui/base/ime/chromeos/mock_input_method_manager.cc

Index: ui/base/ime/chromeos/mock_input_method_manager.cc
diff --git a/ui/base/ime/chromeos/mock_input_method_manager.cc b/ui/base/ime/chromeos/mock_input_method_manager.cc
index a28f490ee098993c70e1c5a2aabae56138a1d6ba..60af4b6e515375d4123c38d1a514a9bc80ce9476 100644
--- a/ui/base/ime/chromeos/mock_input_method_manager.cc
+++ b/ui/base/ime/chromeos/mock_input_method_manager.cc
@@ -8,13 +8,7 @@
 
 namespace chromeos {
 namespace input_method {
-
 MockInputMethodManager::State::State() {}
-
-scoped_refptr<InputMethodManager::State> MockInputMethodManager::State::Clone()
-    const {
-  return nullptr;
-}
 
 void MockInputMethodManager::State::AddInputMethodExtension(
     const std::string& extension_id,