Make Interaction Media Features MQ dynamic on Windows.

ui/events/devices/input_device_observer_win.h

Index: ui/events/devices/input_device_observer_win.h
diff --git a/ui/events/devices/input_device_observer_win.h b/ui/events/devices/input_device_observer_win.h
new file mode 100644
index 0000000000000000000000000000000000000000..5579e25ddc2cbb05dd82a75301856d78be878b31
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+++ b/ui/events/devices/input_device_observer_win.h
@@ -0,0 +1,47 @@
+// Copyright (c) 2017 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_DEVICE_OBSERVER_WIN_H_
+#define CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_DEVICE_OBSERVER_WIN_H_
+
+#include "base/observer_list.h"
+#include "base/win/registry.h"
+#include "ui/events/devices/input_device_event_observer.h"
+
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}
+
+namespace ui {
+class EVENTS_DEVICES_EXPORT InputDeviceObserverWin {
+ public:
+  static InputDeviceObserverWin* GetInstance();
+  ~InputDeviceObserverWin();
+
+  void AddObserver(InputDeviceEventObserver* observer);
+  void RemoveObserver(InputDeviceEventObserver* observer);
+
+ protected:
+  InputDeviceObserverWin();
+
+ private:
+  void OnRegistryKeyChanged(base::win::RegKey* key);
+  void NotifyObserversKeyboardDeviceConfigurationChanged();
+  void NotifyObserversMouseDeviceConfigurationChanged();
+  void NotifyObserversTouchpadDeviceConfigurationChanged();
+
+  std::unique_ptr<base::win::RegKey> registry_key_;
+  base::ObserverList<InputDeviceEventObserver> observers_;
+
+  friend struct base::DefaultSingletonTraits<InputDeviceObserverWin>;
+
+  base::WeakPtrFactory<InputDeviceObserverWin> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(InputDeviceObserverWin);
+};
+
+}  // namespace ui
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_DEVICE_OBSERVER_WIN_H_