Use rewriting to make ChromeOS keyboard F<number> keys produce extended keycodes.

ash/system/chromeos/keyboard_brightness_controller.cc

 // 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.
 
 #include "ash/system/chromeos/keyboard_brightness_controller.h"
 
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "content/public/browser/user_metrics.h"
 #include "ui/base/accelerators/accelerator.h"
 
 namespace ash {
 
 bool KeyboardBrightnessController::HandleKeyboardBrightnessDown(
     const ui::Accelerator& accelerator) {
-  if (accelerator.key_code() == ui::VKEY_F6) {
+  if (accelerator.key_code() == ui::VKEY_BRIGHTNESS_DOWN) {
     Shell::GetInstance()->delegate()->RecordUserMetricsAction(
         UMA_ACCEL_KEYBOARD_BRIGHTNESS_DOWN_F6);
   }
 
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       DecreaseKeyboardBrightness();
   return true;
 }
 
 bool KeyboardBrightnessController::HandleKeyboardBrightnessUp(
     const ui::Accelerator& accelerator) {
-  if (accelerator.key_code() == ui::VKEY_F7) {
+  if (accelerator.key_code() == ui::VKEY_BRIGHTNESS_UP) {
     Shell::GetInstance()->delegate()->RecordUserMetricsAction(
         UMA_ACCEL_KEYBOARD_BRIGHTNESS_UP_F7);
   }
 
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       IncreaseKeyboardBrightness();
   return true;
 }
 
 }  // namespace ash