LibGtkUi: Partition NativeThemeGtk into NativeThemeGtk2 and NativeThemeGtk3

chrome/browser/ui/libgtkui/native_theme_gtk3.h

+// 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_UI_LIBGTKUI_NATIVE_THEME_GTK3_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK3_H_
+
+#include "base/macros.h"
+#include "ui/native_theme/native_theme_base.h"
+
+typedef struct _GtkWidget GtkWidget;
+
+namespace libgtkui {
+
+// A version of NativeTheme that uses GTK3-rendered widgets.
+class NativeThemeGtk3 : public ui::NativeThemeBase {
+ public:
+  static NativeThemeGtk3* instance();
+
+  // Overridden from ui::NativeThemeBase:
+  SkColor GetSystemColor(ColorId color_id) const override;
+
+ private:
+  NativeThemeGtk3();
+  ~NativeThemeGtk3() override;
+
+  // Returns various widgets for theming use.
+  // TODO(thomasanderson): Remove all of these.
+  GtkWidget* GetWindow() const;
+  GtkWidget* GetEntry() const;
+  GtkWidget* GetLabel() const;
+  GtkWidget* GetButton() const;
+  GtkWidget* GetBlueButton() const;
+  GtkWidget* GetTree() const;
+  GtkWidget* GetTooltip() const;
+  GtkWidget* GetMenu() const;
+  GtkWidget* GetMenuItem() const;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeThemeGtk3);
+};
+
+}  // namespace libgtkui
+
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK3_H_