Allow Mojo structs as map keys

components/font_service/public/cpp/font_service_thread.cc

Index: components/font_service/public/cpp/font_service_thread.cc
diff --git a/components/font_service/public/cpp/font_service_thread.cc b/components/font_service/public/cpp/font_service_thread.cc
index 5d9645acea19f90b3da3103fc319a5e6323a2384..81f8394eb81abb628979327b03b019d5e006059b 100644
--- a/components/font_service/public/cpp/font_service_thread.cc
+++ b/components/font_service/public/cpp/font_service_thread.cc
@@ -124,7 +124,7 @@ void FontServiceThread::OnMatchFamilyNameComplete(
   DCHECK_EQ(GetThreadId(), base::PlatformThread::CurrentId());
   pending_waitable_events_.erase(done_event);
 
-  *out_valid = font_identity;
+  *out_valid = !font_identity.is_null();
   if (font_identity) {
     out_font_identity->fID = font_identity->id;
     out_font_identity->fTTCIndex = font_identity->ttc_index;