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

ui/events/keycodes/keyboard_code_conversion.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/keycodes/keyboard_code_conversion.h"
 
 #include <algorithm>
 
 #include "ui/events/event_constants.h"
 #include "ui/events/keycodes/dom3/dom_code.h"
@@ skipping 410 matching lines @@
       // GS
       *character = 0x1D;
       *dom_key = DomKey::CHARACTER;
       *key_code = VKEY_OEM_6;
       return true;
     default:
       return false;
   }
 }
 
+DomKey CharacterToDomKey(base::char16 character) {
+  switch (character) {
+    case 0x08:
+      return DomKey::BACKSPACE;
+    case 0x09:
+      return DomKey::TAB;
+    case 0x0A:
+    case 0x0D:

[Wez, 2015/05/06 23:51:53]

Do we really want to map both of these to Enter? That means we're losing
information on the exact input event? :-S

[kpschoedel, 2015/05/07 16:21:33]

Done.

+      return DomKey::ENTER;
+    case 0x1B:
+      return DomKey::ESCAPE;
+    default:
+      return DomKey::CHARACTER;
+  }
+}
+
 // Returns a Windows-based VKEY for a non-printable DOM Level 3 |key|.
 // The returned VKEY is non-positional (e.g. VKEY_SHIFT).
 KeyboardCode NonPrintableDomKeyToKeyboardCode(DomKey dom_key) {
   for (const auto& it : kDomKeyToKeyboardCodeMap) {
     if (it.dom_key == dom_key)
       return it.key_code;
   }
   return VKEY_UNKNOWN;
 }
 
@@ skipping 80 matching lines @@
       return it.dom_code;
   }
   for (const auto& it : kFallbackKeyboardCodeToDomCodeMap) {
     if (it.key_code == key_code)
       return it.dom_code;
   }
   return DomCode::NONE;
 }
 
 }  // namespace ui