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

chrome/browser/chromeos/system/fake_input_device_settings.h

Index: chrome/browser/chromeos/system/fake_input_device_settings.h
diff --git a/chrome/browser/chromeos/system/fake_input_device_settings.h b/chrome/browser/chromeos/system/fake_input_device_settings.h
index 5138454e9c26fb1b2bb3bee1bd6ac0dad0670f27..bc572de2855bc9fd517f0fa51d7c0dcfe29918c4 100644
--- a/chrome/browser/chromeos/system/fake_input_device_settings.h
+++ b/chrome/browser/chromeos/system/fake_input_device_settings.h
@@ -33,6 +33,9 @@ class FakeInputDeviceSettings : public InputDeviceSettings {
   void ReapplyTouchpadSettings() override;
   void ReapplyMouseSettings() override;
 
+  void SetMouseExists(bool exists);
+  void SetTouchpadExists(bool exists);
+
   const TouchpadSettings& current_touchpad_settings() const {
     return current_touchpad_settings_;
   }
@@ -45,6 +48,9 @@ class FakeInputDeviceSettings : public InputDeviceSettings {
   TouchpadSettings current_touchpad_settings_;
   MouseSettings current_mouse_settings_;
 
+  bool mouse_exists_;
+  bool touchpad_exists_;
+
   DISALLOW_COPY_AND_ASSIGN(FakeInputDeviceSettings);
 };