Set ui::KeyEvent::key_ (DOM Level 3 key) under X11.

ui/events/keycodes/keyboard_code_conversion.h

Index: ui/events/keycodes/keyboard_code_conversion.h
diff --git a/ui/events/keycodes/keyboard_code_conversion.h b/ui/events/keycodes/keyboard_code_conversion.h
index 8b92ba16394eaaebd48ccbacd86bed3ec453bc99..2747590955a673ca72553df08dd54b49e591f7f9 100644
--- a/ui/events/keycodes/keyboard_code_conversion.h
+++ b/ui/events/keycodes/keyboard_code_conversion.h
@@ -70,6 +70,11 @@ EVENTS_BASE_EXPORT bool DomCodeToControlCharacter(DomCode dom_code,
                                                   KeyboardCode* key_code)
     WARN_UNUSED_RESULT;
 
+// Returns the DomKey value associated with an ASCII/Unicode character.
+// All printable characters and most other character codes use
+// DomKey::CHARACTER, but a few ASCII C0 codes have their own DomKey.
+EVENTS_BASE_EXPORT DomKey CharacterToDomKey(uint32 character);
+
 // Returns a Windows-based VKEY for a non-printable DOM Level 3 |key|.
 // The returned VKEY is non-located (e.g. VKEY_SHIFT).
 EVENTS_BASE_EXPORT KeyboardCode