backend: add getters

src/backends/metal/video.rs

@@ -186,6 +186,12 @@ impl BackendDrmDevice for MetalDrmDevice {
         Some(self.id) == self.backend.ctx.get().map(|c| c.dev_id)
     }
 
+    fn direct_scanout_enabled(&self) -> bool {
+        self.direct_scanout_enabled
+            .get()
+            .unwrap_or(self.backend.state.direct_scanout_enabled.get())
+    }
+
     fn create_lease(
         self: Rc<Self>,
         lessee: Rc<dyn BackendDrmLessee>,
@@ -314,6 +320,10 @@ impl BackendDrmDevice for MetalDrmDevice {
             }
         }
     }
+
+    fn flip_margin(&self) -> Option<u64> {
+        Some(self.min_post_commit_margin.get())
+    }
 }
 
 pub struct HandleEvents {