Change mojo geometry structs from using type converters to StructTraits.

mash/webtest/webtest.cc

Index: mash/webtest/webtest.cc
diff --git a/mash/webtest/webtest.cc b/mash/webtest/webtest.cc
index 843a1bc2048463c895059eeca436bbf798e448e9..5ea5fcce935877b0c7e92408ba921ea22bb51bb1 100644
--- a/mash/webtest/webtest.cc
+++ b/mash/webtest/webtest.cc
@@ -14,7 +14,6 @@
 #include "components/mus/public/cpp/window.h"
 #include "components/mus/public/cpp/window_tree_connection.h"
 #include "mash/public/interfaces/launchable.mojom.h"
-#include "mojo/converters/geometry/geometry_type_converters.h"
 #include "mojo/public/c/system/main.h"
 #include "services/navigation/public/interfaces/view.mojom.h"
 #include "services/shell/public/cpp/application_runner.h"
@@ -112,11 +111,11 @@ class UI : public views::WidgetDelegateView,
   void ViewCreated(navigation::mojom::ViewPtr view,
                    navigation::mojom::ViewClientRequest request,
                    bool is_popup,
-                   mojo::RectPtr initial_rect,
+                   const gfx::Rect& initial_rect,
                    bool user_gesture) override {
     views::Widget* window = views::Widget::CreateWindowWithContextAndBounds(
         new UI(webtest_, std::move(view), std::move(request)), nullptr,
-        initial_rect.To<gfx::Rect>());
+        initial_rect);
     window->Show();
     webtest_->AddWindow(window);
   }