Fix GCC incomplete designated initialization bug

For GCC 8.4.0 is important to get all the first initializer in
designated init-list in case of implicit construction. Correct compile
if use explicit construction.

Error example (GCC 8.4.0):
-c ../../ui/events/platform/x11/x11_event_source.cc -o obj/ui/events/platform/x11/x11/x11_event_source.o
../../ui/events/platform/x11/x11_event_source.cc: In function ‘void ui::{anonymous}::InitializeXkb(x11::Connection*)’:
../../ui/events/platform/x11/x11_event_source.cc:78:4: error: no matching function for call to ‘x11::Xkb::SelectEvents(<brace-enclosed initializer list>)’
   });

Change-Id: I80ea8d5f0a14bb8edc1e89e66eb6d1034bd1fec3
Bug: 819294
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2516219Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: José Dapena Paz <jdapena@igalia.com>
Cr-Commit-Position: refs/heads/master@{#823589}

ui/events/platform/x11/x11_event_source.cc

@@ -70,7 +70,7 @@ void InitializeXkb(x11::Connection* connection) {
       }));
 
   constexpr auto kXkbAllMapPartMask = static_cast<x11::Xkb::MapPart>(0xff);
-  xkb.SelectEvents({
+  xkb.SelectEvents(x11::Xkb::SelectEventsRequest{
       .deviceSpec = static_cast<x11::Xkb::DeviceSpec>(x11::Xkb::Id::UseCoreKbd),
       .affectWhich = x11::Xkb::EventType::NewKeyboardNotify,
       .selectAll = x11::Xkb::EventType::NewKeyboardNotify,