Makes sure that an input method doesn't reference to a destroyed object.

ui/base/ime/dummy_input_method.cc

Index: ui/base/ime/dummy_input_method.cc
diff --git a/ui/base/ime/dummy_input_method.cc b/ui/base/ime/dummy_input_method.cc
index b9f69418b076a406c61f84097bda6b531a9a238a..b35313dc32cf4088ac4fea874f6ba1782e63d888 100644
--- a/ui/base/ime/dummy_input_method.cc
+++ b/ui/base/ime/dummy_input_method.cc
@@ -32,6 +32,9 @@ bool DummyInputMethod::OnUntranslatedIMEMessage(const base::NativeEvent& event,
 void DummyInputMethod::SetFocusedTextInputClient(TextInputClient* client) {
 }
 
+void DummyInputMethod::DetachTextInputClient(TextInputClient* client) {
+}
+
 TextInputClient* DummyInputMethod::GetTextInputClient() const {
   return NULL;
 }