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

chrome/browser/android/vr_shell/textures/ui_texture.cc

Index: chrome/browser/android/vr_shell/textures/ui_texture.cc
diff --git a/chrome/browser/android/vr_shell/textures/ui_texture.cc b/chrome/browser/android/vr_shell/textures/ui_texture.cc
index 99b9705361b604169d7d76a013dd8d18ba0a04bf..ef2630dbb34568416757eba26f6961b21d3647ed 100644
--- a/chrome/browser/android/vr_shell/textures/ui_texture.cc
+++ b/chrome/browser/android/vr_shell/textures/ui_texture.cc
@@ -65,6 +65,10 @@ void UiTexture::SetMode(ColorScheme::Mode mode) {
 
 void UiTexture::OnSetMode() {}
 
+const ColorScheme& UiTexture::color_scheme() const {
+  return ColorScheme::GetColorScheme(mode());
+}
+
 std::vector<std::unique_ptr<gfx::RenderText>> UiTexture::PrepareDrawStringRect(
     const base::string16& text,
     const gfx::FontList& font_list,