x11, ozone: Extract DomKey at key event construction

So far, KeyEvent's DomKey extraction used to happen lazily at
GetDomKey()/GetCharacter() calls. Such approach assumes native_event()
is available and holds the underlying XEvent instance so it is able to
extract event info straight out of it.

Document [1] details the effort to eliminate native event usage outside
platform code so that it is possible to migrate Aura/X11's PlatformEvent
away from XEvent* to ui::Event instead (part of broader X11 migration to
Ozone). This issue addressed in this CL is one those remaining cases
listed in doc [1].

CL modifies it to extract DomKey value at KeyEvent construction as it is
done in most Ozone backends (e.g: ozone/evdev). Additionally this
modifies X11EventSourceDefault, currently used by Ozone/X11, to do the
same.

[1] https://docs.google.com/document/d/1Neh2p6f8pew9SPuEAtnJMafozAY7uhAIfhwd43CLETc

Bug: 987939
Change-Id: I9dddad2359b1c345fcb98dabce4506c677269b94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1813417
Commit-Queue: Nick Yamane <nickdiego@igalia.com>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698675}

ui/events/event.cc

@@ -908,9 +908,9 @@ KeyEvent::KeyEvent(const PlatformEvent& native_event, int event_flags)
 
 #if defined(USE_X11)
   NormalizeFlags();
+  key_ = GetDomKeyFromXEvent(native_event);
   SetProperties(GetKeyEventPropertiesFromXKeyEvent(native_event->xkey));
-#endif
-#if defined(OS_WIN)
+#elif defined(OS_WIN)
   // Only Windows has native character events.
   if (is_char_) {
     key_ = DomKey::FromCharacter(static_cast<int32_t>(native_event.wParam));
@@ -1006,11 +1006,6 @@ void KeyEvent::ApplyLayout() const {
 // Native Windows character events always have is_char_ == true,
 // so this is a synthetic or native keystroke event.
 // Therefore, perform only the fallback action.
-#elif defined(USE_X11)
-  if (native_event()) {
-    key_ = GetDomKeyFromXEvent(native_event());
-    return;
-  }
 #elif defined(USE_OZONE)
   if (KeyboardLayoutEngineManager::GetKeyboardLayoutEngine()->Lookup(
           code, flags(), &key_, &dummy_key_code)) {

ui/events/platform/x11/x11_event_source_default.cc

@@ -38,6 +38,20 @@ Event::Properties GetEventPropertiesFromXKeyEvent(const XKeyEvent& xev) {
   return properties;
 }
 
+std::unique_ptr<KeyEvent> CreateKeyEvent(const XEvent& xev) {
+  base::TimeTicks timestamp = EventTimeFromXEvent(xev);
+  ValidateEventTimeClock(&timestamp);
+
+  auto key_event = std::make_unique<KeyEvent>(
+      EventTypeFromXEvent(xev), KeyboardCodeFromXKeyEvent(&xev),
+      CodeFromXEvent(&xev), EventFlagsFromXEvent(xev),
+      GetDomKeyFromXEvent(&xev), timestamp);
+
+  // Attach keyboard group to |key_event|'s properties
+  key_event->SetProperties(GetEventPropertiesFromXKeyEvent(xev.xkey));
+  return key_event;
+}
+
 std::unique_ptr<TouchEvent> CreateTouchEvent(EventType event_type,
                                              const XEvent& xev) {
   std::unique_ptr<TouchEvent> event = std::make_unique<TouchEvent>(
@@ -57,10 +71,11 @@ std::unique_ptr<ui::Event> TranslateXI2EventToEvent(const XEvent& xev) {
   EventType event_type = EventTypeFromXEvent(xev);
   switch (event_type) {
     case ET_KEY_PRESSED:
-    case ET_KEY_RELEASED:
-      return std::make_unique<KeyEvent>(event_type,
-                                        KeyboardCodeFromXKeyEvent(&xev),
-                                        EventFlagsFromXEvent(xev));
+    case ET_KEY_RELEASED: {
+      XEvent xkeyevent = {0};
+      InitXKeyEventFromXIDeviceEvent(xev, &xkeyevent);
+      return CreateKeyEvent(xkeyevent);
+    }
     case ET_MOUSE_PRESSED:
     case ET_MOUSE_MOVED:
     case ET_MOUSE_DRAGGED:
@@ -124,13 +139,8 @@ std::unique_ptr<ui::Event> TranslateXEventToEvent(const XEvent& xev) {
                                           EventTimeFromXEvent(xev), flags, 0);
 
     case KeyPress:
-    case KeyRelease: {
-      auto key_event = std::make_unique<KeyEvent>(
-          EventTypeFromXEvent(xev), KeyboardCodeFromXKeyEvent(&xev), flags);
-      // Attach keyboard group to |key_event|'s properties
-      key_event->SetProperties(GetEventPropertiesFromXKeyEvent(xev.xkey));
-      return key_event;
-    }
+    case KeyRelease:
+      return CreateKeyEvent(xev);
     case ButtonPress:
     case ButtonRelease: {
       switch (EventTypeFromXEvent(xev)) {