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

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

Index: chrome/browser/android/vr_shell/textures/close_button_texture.h
diff --git a/chrome/browser/android/vr_shell/textures/close_button_texture.h b/chrome/browser/android/vr_shell/textures/close_button_texture.h
index 4bd4a0b519ffc7a0c6feb8201ef7cead8a9d1a9a..366fcec68f0b2ab5eb287ce9d5e40656cfbc05d1 100644
--- a/chrome/browser/android/vr_shell/textures/close_button_texture.h
+++ b/chrome/browser/android/vr_shell/textures/close_button_texture.h
@@ -13,6 +13,8 @@ class PointF;
 
 namespace vr_shell {
 
+struct ColorScheme;
+
 class CloseButtonTexture : public ButtonTexture {
  public:
   CloseButtonTexture();
@@ -23,6 +25,7 @@ class CloseButtonTexture : public ButtonTexture {
 
  private:
   void Draw(SkCanvas* sk_canvas, const gfx::Size& texture_size) override;
+  const ColorScheme& color_scheme() const;
 
   gfx::SizeF size_;
 };