servo: Merge #14179 - script: Ensure script is initialized before running script (from emilio:racy-script); r=jdm

<!-- Please describe your changes on the following line: -->

Fixes the race causing #14154. Service workers are ok because they contain explicit synchronization.

r? @asajeffrey or @jdm

Source-Repo: https://github.com/servo/servo
Source-Revision: 6911a2f652468acd9eef2c35d9e27b55d28788fc

servo/components/script/lib.rs

@@ -163,15 +163,17 @@ fn perform_platform_specific_initialization() {
 #[cfg(not(target_os = "linux"))]
 fn perform_platform_specific_initialization() {}
 
+pub fn init_service_workers(sw_senders: SWManagerSenders) {
+    // Spawn the service worker manager passing the constellation sender
+    ServiceWorkerManager::spawn_manager(sw_senders);
+}
+
 #[allow(unsafe_code)]
-pub fn init(sw_senders: SWManagerSenders) {
+pub fn init() {
     unsafe {
         proxyhandler::init();
     }
 
-    // Spawn the service worker manager passing the constellation sender
-    ServiceWorkerManager::spawn_manager(sw_senders);
-
     // Create the global vtables used by the (generated) DOM
     // bindings to implement JS proxies.
     RegisterBindings::RegisterProxyHandlers();

servo/components/servo/lib.rs

@@ -170,6 +170,10 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
             })
         };
 
+        // Important that this call is done in a single-threaded fashion, we
+        // can't defer it after `create_constellation` has started.
+        script::init();
+
         // Create the constellation, which maintains the engine
         // pipelines, including the script and layout threads, as well
         // as the navigation context.
@@ -183,7 +187,7 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
                                                                     webrender_api_sender.clone());
 
         // Send the constellation's swmanager sender to service worker manager thread
-        script::init(sw_senders);
+        script::init_service_workers(sw_senders);
 
         if cfg!(feature = "webdriver") {
             if let Some(port) = opts.webdriver_port {
@@ -339,7 +343,8 @@ pub fn run_content_process(token: String) {
 
     // send the required channels to the service worker manager
     let sw_senders = unprivileged_content.swmanager_senders();
-    script::init(sw_senders);
+    script::init();
+    script::init_service_workers(sw_senders);
 
     unprivileged_content.start_all::<script_layout_interface::message::Msg,
                                      layout_thread::LayoutThread,