Add GetUsbKeyCode dev interface for Pepper key events

ppapi/api/ppb_input_event.idl

 /* Copyright (c) 2012 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 defines the Input Event interfaces.
  */
 
 label Chrome {
@@ skipping 206 matching lines @@
    * knows you do not need to handle touch events, it can handle them at a
    * higher level and achieve higher performance.
    */
   PP_INPUTEVENT_CLASS_TOUCH = 1 << 3,
 
   /**
    * Identifies IME composition input events.
    *
    * Request this input event class if you allow on-the-spot IME input.
    */
-  PP_INPUTEVENT_CLASS_IME = 1 << 4
+  PP_INPUTEVENT_CLASS_IME = 1 << 4,
+
+  /**
+   * Requests low-level keyboard events. Instead of Windows virtual key code,
+   * this will return USB scan codes for each key press.
+   * 
+   * As with PP_INPUTEVENT_CLASS_KEYBOARD, you will usually want to request
+   * filtered mode so you can pass on the events.

[Wez, 2012/02/07 23:48:13]

nit: I'm not convinced that this is true for low-level input.

[garykac, 2012/02/09 14:26:04]

No longer applicable.

+   */
+  PP_INPUTEVENT_CLASS_LOWLEVEL_KEYBOARD_Dev = 1 << 5
 };
 
 /**
  * The <code>PPB_InputEvent</code> interface contains pointers to several
  * functions related to generic input events on the browser.
  */
 [version=1.0, macro="PPB_INPUT_EVENT_INTERFACE"]
 interface PPB_InputEvent {
   /**
    * RequestInputEvent() requests that input events corresponding to the given
@@ skipping 484 matching lines @@
    * @param[in] character_event A <code>PP_Resource</code> corresponding to a
    * keyboard event.
    *
    * @return A string var representing a single typed character for character
    * input events. For non-character input events the return value will be an
    * undefined var.
    */
   PP_Var GetCharacterText([in] PP_Resource character_event);
 };