Monitor the system native frame color on Win 10.

chrome/browser/themes/theme_service_win.h

Index: chrome/browser/themes/theme_service_win.h
diff --git a/chrome/browser/themes/theme_service_win.h b/chrome/browser/themes/theme_service_win.h
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+// Copyright 2016 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 CHROME_BROWSER_THEMES_THEME_SERVICE_WIN_H_
+#define CHROME_BROWSER_THEMES_THEME_SERVICE_WIN_H_
+
+#include "base/win/registry.h"
+#include "chrome/browser/themes/theme_service.h"
+
+class ThemeServiceWin : public ThemeService {
+ public:
+  ThemeServiceWin();
+  ~ThemeServiceWin() override;
+
+ private:
+  // ThemeService:
+  bool ShouldUseNativeFrame() const override;
+  SkColor GetDefaultColor(int id, bool incognito) const override;
+
+  // Returns true if the window frame color is determined by the DWM, i.e. this
+  // is a native frame on Windows 10.
+  bool ShouldUseDwmFrameColor() const;
+
+  // Callback executed when |dwm_key_| is updated.  This re-reads the active
+  // frame color and updates |dwm_frame_color_|.
+  void OnDwmKeyUpdated();
+
+  // Registry key containing the params that determine the DWM frame color.
+  // This is only initialized on Windows 10.
+  scoped_ptr<base::win::RegKey> dwm_key_;
+
+  // The DWM frame color, if available; white otherwise.
+  SkColor dwm_frame_color_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThemeServiceWin);
+};
+
+#endif  // CHROME_BROWSER_THEMES_THEME_SERVICE_WIN_H_