[KeyboardEvent] Add embedder APIs to translate between Dom |key| enum and strings

ui/events/keycodes/dom/dom_key_data.inc

 // Copyright 2014 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.
 
 // This file has no header guard because it is explicily intended
 // to be included more than once with different definitions of the
 // macros DOM_KEY_MAP and DOM_KEY_MAP_DECLARATION.
 
 // This is a table of DOM Level 3 .key values, used to generate identifiers
 // (enums) and string tables. These names are defined by:
@@ skipping 10 matching lines @@
 
 DOM_KEY_MAP_DECLARATION {
 
   // The first entry, whose enum value will be zero, is reserved to mean
   // no value; there is no corresponding DOM string. (This is not the same
   // as the valid DOM .key value 'Unidentified'.)
 
   //          Key                     Enum
   DOM_KEY_MAP(nullptr,                NONE),  // No value
 
-  // A value of DomKey::CHARACTER indicates that the KeyboardEvent |key|
-  // string is determined by the Unicode character interpretation and is
-  // not one of the fixed string values.
-  DOM_KEY_MAP(nullptr,                CHARACTER),
-
   // =========================================================
   // Special Key Values
   // http://www.w3.org/TR/DOM-Level-3-Events-key/#keys-special
   // =========================================================
 
   // Unable to identify another key value
   DOM_KEY_MAP("Unidentified",         UNIDENTIFIED),
 
   // ==========================================================
   // Modifier Keys
@@ skipping 326 matching lines @@
   DOM_KEY_MAP("STBInput",             STB_INPUT),
   DOM_KEY_MAP("STBPower",             STB_POWER),
   DOM_KEY_MAP("Subtitle",             SUBTITLE),
   DOM_KEY_MAP("Teletext",             TELETEXT),
   DOM_KEY_MAP("TV",                   T_V),
   DOM_KEY_MAP("TVInput",              TV_INPUT),
   DOM_KEY_MAP("TVPower",              TV_POWER),
   DOM_KEY_MAP("VideoModeNext",        VIDEO_MODE_NEXT),
   DOM_KEY_MAP("Wink",                 WINK),
   DOM_KEY_MAP("ZoomToggle",           ZOOM_TOGGLE),
+
+  // A value of DomKey::CHARACTER indicates that the KeyboardEvent |key|
+  // string is determined by the Unicode character interpretation and is
+  // not one of the fixed string values.
+  DOM_KEY_MAP(nullptr,                CHARACTER),

[dtapuska, 2015/08/13 13:36:48]

Should a comment be added here that CHARACTER is assumed to be the last item in
the enumeration?

Or should there be a special define for the end of the enumeration that matches
the last most item instead of referring to CHARACTER everywhere?

 };