[KeyboardEvent] Use DOM |code| rather than Windows-based key code

ui/events/keycodes/keyboard_code_conversion.h

 // 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.
 
 #ifndef UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_
 #define UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_
 
 #include "base/strings/string16.h"
 #include "ui/events/events_base_export.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
 namespace ui {
 
 enum class DomCode;
 enum class DomKey;
 
-// Helper functions to get the meaning of a Windows key code in a
+// Helper functions to get the meaning of a  DOM |code| in a
 // platform independent way. It supports control characters as well.
 // It assumes a US keyboard layout is used, so it may only be used when there
 // is no native event or no better way to get the character.
+//
 // For example, if a virtual keyboard implementation can only generate key
 // events with key_code and flags information, then there is no way for us to
 // determine the actual character that should be generate by the key. Because
 // a key_code only represents a physical key on the keyboard, it has nothing
 // to do with the actual character printed on that key. In such case, the only
 // thing we can do is to assume that we are using a US keyboard and get the
-// character according to US keyboard layout definition.
-// If a virtual keyboard implementation wants to support other keyboard
-// layouts, that may generate different text for a certain key than on a US
-// keyboard, a special native event object should be introduced to carry extra
-// information to help determine the correct character.
-// Take XKeyEvent as an example, it contains not only keycode and modifier
-// flags but also group and other extra XKB information to help determine the
-// correct character. That's why we can use XLookupString() function to get
-// the correct text generated by a X key event (See how is GetCharacter()
-// implemented in event_x.cc).
-EVENTS_BASE_EXPORT base::char16 GetCharacterFromKeyCode(KeyboardCode key_code,
-                                                        int flags);
-EVENTS_BASE_EXPORT bool GetMeaningFromKeyCode(KeyboardCode key_code,
-                                              int flags,
-                                              DomKey* dom_key,
-                                              base::char16* character);
+// character according to US keyboard layout definition. Preferably, such
+// events should be created using a full KeyEvent constructor, explicitly
+// specifying the character and DOM 3 values as well as the legacy VKEY.
+EVENTS_BASE_EXPORT base::char16 DomCodeToCharacter(DomCode dom_code,
+                                                   int flags);
+
+EVENTS_BASE_EXPORT bool DomCodeToMeaning(DomCode dom_code,
+                                         int flags,
+                                         DomKey* dom_key,
+                                         base::char16* character,
+                                         KeyboardCode* key_code);
+
+// Obtains the control character corresponding to a physical key;
+// that is, the meaning of the physical key state (dom_code, and flags
+// containing EF_CONTROL_DOWN) under a specific US English layout.
+// Returns true and sets the output parameters if the (dom_code, flags) pair
+// is interpreted as a control character; otherwise the output parameters
+// ara untouched.
+EVENTS_BASE_EXPORT bool DomCodeToControlCharacter(DomCode dom_code,
+                                                  int flags,
+                                                  DomKey* dom_key,
+                                                  base::char16* character,
+                                                  KeyboardCode* key_code);
+
+// Returns the DomKey value associated with an ASCII/Unicode character
+// All printable characters are most other character codes use
+// DomKey::CHARACTER, but a few ASCII C0 codes have their own DomKey.
+EVENTS_BASE_EXPORT DomKey CharacterToDomKey(base::char16 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
+NonPrintableDomKeyToKeyboardCode(DomKey dom_key);
+
+// Returns the Windows-based VKEY value corresponding to a DOM Level 3 |code|.
+// The returned VKEY is located (e.g. VKEY_LSHIFT) and considered as a
+// layout-independent physical key (e.g. DomCode::KEY_Q -> VKEY_Q) which is
+// based on the US English Layout. This should only be used as a last resort
+// when other means of determining a suitable VKEY fails.
+EVENTS_BASE_EXPORT KeyboardCode DomCodeToKeyboardCode(DomCode dom_code);
 
 // Determine the non-located VKEY corresponding to a located VKEY.
 // Most modifier keys have two kinds of KeyboardCode: located (e.g.
 // VKEY_LSHIFT and VKEY_RSHIFT), that indentify one of two specific
 // physical keys, and non-located (e.g. VKEY_SHIFT) that identify
 // only the operation.
 EVENTS_BASE_EXPORT KeyboardCode
 LocatedToNonLocatedKeyboardCode(KeyboardCode key_code);
 
 // Determine the located VKEY corresponding to a non-located VKEY.
 EVENTS_BASE_EXPORT KeyboardCode
 NonLocatedToLocatedKeyboardCode(KeyboardCode key_code, DomCode dom_code);
 
+// Returns a DOM Level 3 |code| from a Windows based VKEY value.
+// This assumes a US Layout and should only be used when |code| cannot be
+// determined from a physical scan code.
+// For example, when a key event was generated synthetically by JS with
+// onlay a VKEY value supplied.
+EVENTS_BASE_EXPORT DomCode KeyboardCodeToDomCode(KeyboardCode key_code);
+
+// Returns the ui::EventFlags value associated with a modifier key,
+// or 0 (EF_NONE) if the key is not a modifier.
+EVENTS_BASE_EXPORT int ModifierDomKeyToEventFlag(DomKey key);
+
 }  // namespace ui
 
 #endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_H_