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

chrome/browser/chromeos/system/input_device_settings.h

Index: chrome/browser/chromeos/system/input_device_settings.h
diff --git a/chrome/browser/chromeos/system/input_device_settings.h b/chrome/browser/chromeos/system/input_device_settings.h
index da1945861c68b801f8bc92fc0383d4326bbc4bd7..b02ebf556e0c854b3dbb2a5bc5fae16fe8abbb72 100644
--- a/chrome/browser/chromeos/system/input_device_settings.h
+++ b/chrome/browser/chromeos/system/input_device_settings.h
@@ -155,16 +155,21 @@ class CHROMEOS_EXPORT InputDeviceSettings {
  public:
   typedef base::Callback<void(bool)> DeviceExistsCallback;
 
+  // Interface for faking touchpad and mouse. Accessed through
+  // GetFakeInterface(), implemented only in FakeInputDeviceSettings.
+  class FakeInterface {
+   public:
+    virtual void set_touchpad_exists(bool exists) = 0;
+    virtual void set_mouse_exists(bool exists) = 0;
+    virtual const TouchpadSettings& current_touchpad_settings() const = 0;
+    virtual const MouseSettings& current_mouse_settings() const = 0;
+  };
+
   virtual ~InputDeviceSettings() {}
 
   // Returns current instance of InputDeviceSettings.
   static InputDeviceSettings* Get();
 
-  // Replaces current instance with |test_settings|. Takes ownership of
-  // |test_settings|. Default implementation could be returned back by passing
-  // NULL to this method.
-  static void SetSettingsForTesting(InputDeviceSettings* test_settings);
-
   // Returns true if UI should implement enhanced keyboard support for cases
   // where other input devices like mouse are absent.
   static bool ForceKeyboardDrivenUINavigation();
@@ -179,8 +184,8 @@ class CHROMEOS_EXPORT InputDeviceSettings {
   void ToggleTouchscreen();
   void ToggleTouchpad();
 
-  // Calls |callback| asynchronously after determining if a touchpad is
-  // connected.
+  // Calls |callback|, possibly asynchronously, after determining if a touchpad
+  // is connected.
   virtual void TouchpadExists(const DeviceExistsCallback& callback) = 0;
 
   // Updates several touchpad settings at a time. Updates only settings that
@@ -204,7 +209,8 @@ class CHROMEOS_EXPORT InputDeviceSettings {
   // Turns natural scrolling on/off for all devices except wheel mice
   virtual void SetNaturalScroll(bool enabled) = 0;
 
-  // Calls |callback| asynchronously after determining if a mouse is connected.
+  // Calls |callback|, possibly asynchronously, after determining if a mouse is
+  // connected.
   virtual void MouseExists(const DeviceExistsCallback& callback) = 0;
 
   // Updates several mouse settings at a time. Updates only settings that
@@ -225,6 +231,9 @@ class CHROMEOS_EXPORT InputDeviceSettings {
   // Reapplies previously set mouse settings.
   virtual void ReapplyMouseSettings() = 0;
 
+  // Returns an interface for faking settings, or nullptr.
+  virtual FakeInterface* GetFakeInterface() = 0;
+
  private:
   virtual void SetInternalTouchpadEnabled(bool enabled) {}
   virtual void SetTouchscreensEnabled(bool enabled) {}