Auto merge of #22938 - asajeffrey:webvr-future-frame-data, r=paulrouget

Use webvr future_frame_data to avoid blocking the WebGL thread

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This PR fixes a potential deadlock caused by the WebGL thread being blocked on a VR device. Rather than blocking on the VR device, it forwards a future to the script thread, and then then script thread blocks.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes do not require tests because it's fixing a potential deadlock

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1 files changed, 2 insertions, 5 deletions

diff --git a/components/webvr/webvr_thread.rs b/components/webvr/webvr_thread.rs
index 2d55fa8deac..4ce25bccb50 100644
--- a/components/webvr/webvr_thread.rs
+++ b/components/webvr/webvr_thread.rs
@@ -385,11 +385,8 @@ impl webgl::WebVRRenderHandler for WebVRCompositorHandler {
             },
             webgl::WebVRCommand::SyncPoses(compositor_id, near, far, sender) => {
                 if let Some(compositor) = self.compositors.get(&compositor_id) {
-                    let pose = unsafe {
-                        (*compositor.0).sync_poses();
-                        (*compositor.0).synced_frame_data(near, far).to_bytes()
-                    };
-                    let _ = sender.send(Ok(pose.into()));
+                    let pose = unsafe { (*compositor.0).future_frame_data(near, far) };
+                    let _ = sender.send(Ok(pose));
                 } else {
                     let _ = sender.send(Err(()));
                 }