[VrShell] Centralize color handling and enable close button on fullscreen

chrome/browser/android/vr_shell/textures/close_button_texture.h

 // Copyright 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 CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_CLOSE_BUTTON_TEXTURE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_CLOSE_BUTTON_TEXTURE_H_
 
 #include "chrome/browser/android/vr_shell/textures/button_texture.h"
 
 namespace gfx {
 class PointF;
 }  // namespace gfx
 
 namespace vr_shell {
 
+struct ColorScheme;
+
 class CloseButtonTexture : public ButtonTexture {
  public:
   CloseButtonTexture();
   ~CloseButtonTexture() override;
   gfx::Size GetPreferredTextureSize(int width) const override;
   gfx::SizeF GetDrawnSize() const override;
   bool HitTest(const gfx::PointF& point) const override;
 
  private:
   void Draw(SkCanvas* sk_canvas, const gfx::Size& texture_size) override;
+  const ColorScheme& color_scheme() const;
 
   gfx::SizeF size_;
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_CLOSE_BUTTON_TEXTURE_H_