Bug 1692629 - Add profiler idleness annotations for IPC I/O thread on Windows. r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D105092

ipc/chromium/src/base/message_pump_win.cc

@@ -481,6 +481,7 @@ bool MessagePumpForIO::GetIOItem(DWORD timeout, IOItem* item) {
   memset(item, 0, sizeof(*item));
   ULONG_PTR key = 0;
   OVERLAPPED* overlapped = NULL;
+  AUTO_PROFILER_LABEL("MessagePumpForIO::GetIOItem::Wait", IDLE);
   if (!GetQueuedCompletionStatus(port_.Get(), &item->bytes_transfered, &key,
                                  &overlapped, timeout)) {
     if (!overlapped) return false;  // Nothing in the queue.