Auto merge of #23746 - asajeffrey:webgl-lies-damn-lies-and-serialization, r=Manishearth

WebGLSender doesn't really implement Serializable

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Add an API which turns a `WebGLSender` into something that is actually serializable.

---
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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 this is fixing a panic

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2 files changed, 38 insertions, 2 deletions

diff --git a/components/canvas_traits/webgl.rs b/components/canvas_traits/webgl.rs
index 2df61282863..16b9d2c0b5e 100644
--- a/components/canvas_traits/webgl.rs
+++ b/components/canvas_traits/webgl.rs
@@ -7,7 +7,7 @@ use gleam::gl;
 use gleam::gl::GLsync;
 use gleam::gl::GLuint;
 use gleam::gl::Gl;
-use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender, IpcSharedMemory};
+use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender, IpcSender, IpcSharedMemory};
 use pixels::PixelFormat;
 use std::borrow::Cow;
 use std::fmt;
@@ -175,10 +175,25 @@ impl WebGLMsgSender {
     pub fn send_dom_to_texture(&self, command: DOMToTextureCommand) -> WebGLSendResult {
         self.sender.send(WebGLMsg::DOMToTextureCommand(command))
     }
+
+    pub fn webxr_external_image_api(&self) -> impl webxr_api::WebGLExternalImageApi {
+        SerializableWebGLMsgSender {
+            ctx_id: self.ctx_id,
+            sender: self.sender.to_ipc(),
+        }
+    }
+}
+
+// WegGLMsgSender isn't actually serializable, despite what it claims.
+#[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]
+struct SerializableWebGLMsgSender {
+    ctx_id: WebGLContextId,
+    #[ignore_malloc_size_of = "channels are hard"]
+    sender: IpcSender<WebGLMsg>,
 }
 
 #[typetag::serde]
-impl webxr_api::WebGLExternalImageApi for WebGLMsgSender {
+impl webxr_api::WebGLExternalImageApi for SerializableWebGLMsgSender {
     fn lock(&self) -> Result<(GLuint, Size2D<i32>, GLsync), webxr_api::Error> {
         let (sender, receiver) = webgl_channel().or(Err(webxr_api::Error::CommunicationError))?;
         self.sender
diff --git a/components/canvas_traits/webgl_channel/mod.rs b/components/canvas_traits/webgl_channel/mod.rs
index aa448b75867..c9b2137a287 100644
--- a/components/canvas_traits/webgl_channel/mod.rs
+++ b/components/canvas_traits/webgl_channel/mod.rs
@@ -8,6 +8,7 @@ mod ipc;
 mod mpsc;
 
 use crate::webgl::WebGLMsg;
+use ipc_channel::ipc::IpcSender;
 use serde::{Deserialize, Serialize};
 use servo_config::opts;
 use std::fmt;
@@ -93,6 +94,26 @@ impl WebGLChan {
     pub fn send(&self, msg: WebGLMsg) -> WebGLSendResult {
         self.0.send(msg)
     }
+
+    pub fn to_ipc(&self) -> IpcSender<WebGLMsg> {
+        match self.0 {
+            WebGLSender::Ipc(ref sender) => sender.clone(),
+            WebGLSender::Mpsc(ref mpsc_sender) => {
+                let (sender, receiver) =
+                    ipc_channel::ipc::channel().expect("IPC Channel creation failed");
+                let mpsc_sender = mpsc_sender.clone();
+                ipc_channel::router::ROUTER.add_route(
+                    receiver.to_opaque(),
+                    Box::new(move |message| {
+                        if let Ok(message) = message.to() {
+                            let _ = mpsc_sender.send(message);
+                        }
+                    }),
+                );
+                sender
+            },
+        }
+    }
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]