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

chrome/browser/ui/ash/brightness_controller_chromeos.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 "chrome/browser/ui/ash/brightness_controller_chromeos.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"
 
 bool BrightnessController::HandleBrightnessDown(
     const ui::Accelerator& accelerator) {
-  if (accelerator.key_code() == ui::VKEY_F6)
+  if (accelerator.key_code() == ui::VKEY_BRIGHTNESS_DOWN)
     content::RecordAction(
         content::UserMetricsAction("Accel_BrightnessDown_F6"));
 
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       DecreaseScreenBrightness(true);
   return true;
 }
 
 bool BrightnessController::HandleBrightnessUp(
     const ui::Accelerator& accelerator) {
-  if (accelerator.key_code() == ui::VKEY_F7)
+  if (accelerator.key_code() == ui::VKEY_BRIGHTNESS_UP)
     content::RecordAction(content::UserMetricsAction("Accel_BrightnessUp_F7"));
 
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       IncreaseScreenBrightness();
   return true;
 }
 
 void BrightnessController::SetBrightnessPercent(double percent, bool gradual) {
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       SetScreenBrightnessPercent(percent, gradual);
 }
 
 void BrightnessController::GetBrightnessPercent(
     const base::Callback<void(double)>& callback) {
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->
       GetScreenBrightnessPercent(callback);
 }