### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

v14.0.0-nightly.20210426

### What operating system are you using?

Windows

### Operating System Version

Windows 10

### What arch are you using?

x64

### Last Known Working Electron version

v14.0.0-nightly.20210413

### Expected Behavior

`BrowserViews` load their `webContents`

### Actual Behavior

BrowserViews will not load `webContents` properly.

### Testcase Gist URL

https://gist.github.com/712a2fde2757736c9dbf6c3e7e0aa18b

### Additional Information

Bisected range: https://github.com/electron/electron/compare/v14.0.0-nightly.20210413...v14.0.0-nightly.20210426
shell/browser/native_browser_view_views.h
void SetAutoResizeFlags(uint8_t flags) override;
  void SetBounds(const gfx::Rect& bounds) override;
  gfx::Rect GetBounds() override;
  void SetBackgroundColor(SkColor color) override;
  void UpdateDraggableRegions(
      const std::vector<mojom::DraggableRegionPtr>& regions) override;
  SkRegion* draggable_region() const { return draggable_region_.get(); }
 private:
  void ResetAutoResizeProportions();
  uint8_t auto_resize_flags_ = 0;
  bool auto_horizontal_proportion_set_ = false;
  float auto_horizontal_proportion_width_ = 0.;
  float auto_horizontal_proportion_left_ = 0.;
  bool auto_vertical_proportion_set_ = false;
  float auto_vertical_proportion_height_ = 0.;
  float auto_vertical_proportion_top_ = 0.;
  std::unique_ptr<SkRegion> draggable_region_;
  DISALLOW_COPY_AND_ASSIGN(NativeBrowserViewViews);
};
}  
#endif