ui/compositor: use an IO message loop on posix instead of DEFAULT

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 8b9b9c31b221d3089bead79127ce297838ae5330..bf6bfbc45b12799950840a48fe351a83c7469d6a 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -491,7 +491,18 @@ void Compositor::Initialize() {
 #endif
   if (use_thread) {
     g_compositor_thread = new base::Thread("Browser Compositor");
+#if defined(OS_POSIX)
+    // Workaround for crbug.com/293736
+    // On Posix, MessagePumpDefault uses system time, so delayed tasks (for
+    // compositor scheduling) work incorrectly across system time changes (e.g.
+    // tlsdate). So instead, use an IO loop, which uses libevent, that uses
+    // monotonic time (immune to these problems).
+    base::Thread::Options options;
+    options.message_loop_type = base::MessageLoop::TYPE_IO;
+    g_compositor_thread->StartWithOptions(options);
+#else
     g_compositor_thread->Start();
+#endif
   }
 
   DCHECK(!g_compositor_initialized) << "Compositor initialized twice.";