Change mojo geometry structs from using type converters to StructTraits.

components/bitmap_uploader/bitmap_uploader.h

Index: components/bitmap_uploader/bitmap_uploader.h
diff --git a/components/bitmap_uploader/bitmap_uploader.h b/components/bitmap_uploader/bitmap_uploader.h
index 7b8f062048ae07005c67d7c8a4bff2acdd0b4589..e967fe22c0de78d4bc6e76d7887f15e058f0d9b5 100644
--- a/components/bitmap_uploader/bitmap_uploader.h
+++ b/components/bitmap_uploader/bitmap_uploader.h
@@ -59,7 +59,7 @@ class BITMAP_UPLOADER_EXPORT BitmapUploader
  private:
   void Upload();
 
-  uint32_t BindTextureForSize(const mojo::Size size);
+  uint32_t BindTextureForSize(const gfx::Size& size);
 
   uint32_t TextureFormat() const {
     return format_ == BGRA ? GL_BGRA_EXT : GL_RGBA;
@@ -77,7 +77,6 @@ class BITMAP_UPLOADER_EXPORT BitmapUploader
   std::unique_ptr<mus::WindowSurface> surface_;
   std::unique_ptr<mus::GLES2Context> gles2_context_;
 
-  mojo::Size size_;
   uint32_t color_;
   int width_;
   int height_;