Remove the 2-level input method system & InputMethodBridge.

ui/views/controls/textfield/textfield.h

Index: ui/views/controls/textfield/textfield.h
diff --git a/ui/views/controls/textfield/textfield.h b/ui/views/controls/textfield/textfield.h
index 91df9b5bb5d928d8ad872f50f25c19c62dd14f58..1c19d7f39dfec51a76a85691c97b51079fe0cc18 100644
--- a/ui/views/controls/textfield/textfield.h
+++ b/ui/views/controls/textfield/textfield.h
@@ -218,7 +218,6 @@ class VIEWS_EXPORT Textfield : public View,
   bool OnMouseDragged(const ui::MouseEvent& event) override;
   void OnMouseReleased(const ui::MouseEvent& event) override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
-  ui::TextInputClient* GetTextInputClient() override;
   void OnGestureEvent(ui::GestureEvent* event) override;
   bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
   void AboutToRequestFocusFromTabTraversal(bool reverse) override;