[metal] Do not keep the view around that the surface was created from

We do not use it, and the layer itself is already retained, so it won't
be de-allocated from under our feet.

wgpu-hal/src/metal/mod.rs

@@ -342,7 +342,6 @@ pub struct Device {
 }
 
 pub struct Surface {
- view: Option<NonNull<objc::runtime::Object>>,
  render_layer: Mutex<metal::MetalLayer>,
  swapchain_format: RwLock<Option<wgt::TextureFormat>>,
  extent: RwLock<wgt::Extent3d>,

wgpu-hal/src/metal/surface.rs

@@ -64,9 +64,8 @@ impl HalManagedMetalLayerDelegate {
 }
 
 impl super::Surface {
- fn new(view: Option<NonNull<Object>>, layer: metal::MetalLayer) -> Self {
+ fn new(layer: metal::MetalLayer) -> Self {
  Self {
- view,
  render_layer: Mutex::new(layer),
  swapchain_format: RwLock::new(None),
  extent: RwLock::new(wgt::Extent3d::default()),
@@ -86,16 +85,14 @@ impl super::Surface {
  // SAFETY: The layer is an initialized instance of `CAMetalLayer`, and
  // we transfer the retain count to `MetalLayer` using `ManuallyDrop`.
  let layer = unsafe { metal::MetalLayer::from_ptr(layer.cast()) };
- let view: *mut Object = msg_send![view.as_ptr(), retain];
- let view = NonNull::new(view).expect("retain should return the same object");
- Self::new(Some(view), layer)
+ Self::new(layer)
  }
 
  pub unsafe fn from_layer(layer: &metal::MetalLayerRef) -> Self {
  let class = class!(CAMetalLayer);
  let proper_kind: BOOL = msg_send![layer, isKindOfClass: class];
  assert_eq!(proper_kind, YES);
- Self::new(None, layer.to_owned())
+ Self::new(layer.to_owned())
  }
 
  /// Get or create a new `CAMetalLayer` associated with the given `NSView`
@@ -279,16 +276,6 @@ impl super::Surface {
  }
 }
 
-impl Drop for super::Surface {
- fn drop(&mut self) {
- if let Some(view) = self.view {
- unsafe {
- let () = msg_send![view.as_ptr(), release];
- }
- }
- }
-}
-
 impl crate::Surface for super::Surface {
  type A = super::Api;