Remove the 2-level input method system & InputMethodBridge.

ui/base/ime/dummy_text_input_client.h

Index: ui/base/ime/dummy_text_input_client.h
diff --git a/ui/base/ime/dummy_text_input_client.h b/ui/base/ime/dummy_text_input_client.h
index f1cd486ff93c07be0e96330866a79c15039d0c11..2c26f89eca77e3087ca0da185333ac88c16ee170 100644
--- a/ui/base/ime/dummy_text_input_client.h
+++ b/ui/base/ime/dummy_text_input_client.h
@@ -22,7 +22,6 @@ class DummyTextInputClient : public TextInputClient {
   void ClearCompositionText() override;
   void InsertText(const base::string16& text) override;
   void InsertChar(base::char16 ch, int flags) override;
-  gfx::NativeWindow GetAttachedWindow() const override;
   TextInputType GetTextInputType() const override;
   TextInputMode GetTextInputMode() const override;
   int GetTextInputFlags() const override;