Remove the 2-level input method system & InputMethodBridge.

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 351cf5774bcaa36ac754f985ebd71c85939cb31d..759218fc81d6a02e032f3088a03355744693df2e 100644
--- a/ui/keyboard/keyboard_controller.cc
+++ b/ui/keyboard/keyboard_controller.cc
@@ -63,9 +63,6 @@ class KeyboardWindowDelegate : public aura::WindowDelegate {
   gfx::Size GetMaximumSize() const override { return gfx::Size(); }
   void OnBoundsChanged(const gfx::Rect& old_bounds,
                        const gfx::Rect& new_bounds) override {}
-  ui::TextInputClient* GetFocusedTextInputClient() override {
-    return nullptr;
-  }
   gfx::NativeCursor GetCursor(const gfx::Point& point) override {
     return gfx::kNullCursor;
   }