Make destructor public in Observer

Make destructor public in CameraPrivacySwitchObserver.
This is needed in order to use the type with unique_ptr.
The abstractness of the class is sufficiently assured by the existing
virtual abstract method.

Change-Id: Ibaa0610ec8b548bf65e287a65f92833f10f4aecc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3783035
Commit-Queue: Wei Lee <wtlee@chromium.org>
Auto-Submit: Jan Láník <janlanik@google.com>
Commit-Queue: Jan Láník <janlanik@google.com>
Reviewed-by: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1032462}

media/capture/video/chromeos/camera_hal_dispatcher_impl.h

@@ -106,11 +106,10 @@ class FailedCameraHalServerCallbacks final
 class CAPTURE_EXPORT CameraPrivacySwitchObserver
     : public base::CheckedObserver {
  public:
+  ~CameraPrivacySwitchObserver() override = default;
+
   virtual void OnCameraPrivacySwitchStatusChanged(
       cros::mojom::CameraPrivacySwitchState state) = 0;
-
- protected:
-  ~CameraPrivacySwitchObserver() override = default;
 };
 
 // The CameraHalDispatcherImpl hosts and waits on the unix domain socket