Change mojo geometry structs from using type converters to StructTraits.

ash/sysui/keyboard_ui_mus.h

Index: ash/sysui/keyboard_ui_mus.h
diff --git a/ash/sysui/keyboard_ui_mus.h b/ash/sysui/keyboard_ui_mus.h
index e848bfcbf340af47b6013bfbc3a84df4e7c4f5d7..623c2ec487477e12516a226b195dfbed880b0d92 100644
--- a/ash/sysui/keyboard_ui_mus.h
+++ b/ash/sysui/keyboard_ui_mus.h
@@ -35,7 +35,7 @@ class KeyboardUIMus : public KeyboardUI,
   void OnKeyboardStateChanged(bool is_enabled,
                               bool is_visible,
                               uint64_t display_id,
-                              mojo::RectPtr bounds) override;
+                              const gfx::Rect& bounds) override;
 
  private:
   bool is_enabled_;