Auto merge of #26036 - gterzian:add_ipc_router_shutdown, r=Manishearth

Add ipc router shutdown

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Explicitly shutting down IPC router as part of shutdown, for contexts see https://github.com/servo/servo/pull/25685#pullrequestreview-364604068

Note that the call to `shutdown` is idempotent, so it shouldn't matter whether the call in the constellation and the script-thread are actually on the same `ROUTER` in single-process mode...

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- [ ] These changes fix #___ (GitHub issue number if applicable)

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components/script/script_thread.rs

@@ -145,6 +145,7 @@ use script_traits::{ScriptToConstellationChan, TimerSchedulerMsg};
 use script_traits::{TouchEventType, TouchId, UntrustedNodeAddress, WheelDelta};
 use script_traits::{UpdatePipelineIdReason, WebrenderIpcSender, WindowSizeData, WindowSizeType};
 use servo_atoms::Atom;
+use servo_config::opts;
 use servo_url::{ImmutableOrigin, MutableOrigin, ServoUrl};
 use std::borrow::Cow;
 use std::cell::Cell;
@@ -2908,6 +2909,12 @@ impl ScriptThread {
             .as_ref()
             .map(|bhm| bhm.unregister());
 
+        // If we're in multiprocess mode, shut-down the IPC router for this process.
+        if opts::multiprocess() {
+            debug!("Exiting IPC router thread in script thread.");
+            ROUTER.shutdown();
+        }
+
         debug!("Exited script thread.");
     }