Use fake Input Device Settings with chrome://device-emulator

chrome/browser/chromeos/system/input_device_settings_impl_ozone.cc

 // 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.
 
 #include "chrome/browser/chromeos/system/input_device_settings.h"
 
 #include "base/macros.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/ozone/public/input_controller.h"
 #include "ui/ozone/public/ozone_platform.h"
@@ skipping 161 matching lines @@
 
 // static
 void InputDeviceSettings::SetSettingsForTesting(
     InputDeviceSettings* test_settings) {
   if (g_test_instance == test_settings)
     return;
   delete g_test_instance;
   g_test_instance = test_settings;
 }
 
+// static
+bool InputDeviceSettings::DidSetSettingsForTesting() {
+  return g_test_instance;
+}
+
 }  // namespace system
 }  // namespace chromeos