[vr] Add incognito coloring

chrome/browser/android/vr_shell/ui_elements/ui_element.cc

 // 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.
 
 #include "chrome/browser/android/vr_shell/ui_elements/ui_element.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "base/time/time.h"
@@ skipping 213 matching lines @@
 
 void UiElement::SetEnabled(bool enabled) {
   visible_ = enabled;
 }
 
 bool UiElement::HitTest(const gfx::PointF& point) const {
   return point.x() >= 0.0f && point.x() <= 1.0f && point.y() >= 0.0f &&
          point.y() <= 1.0f;
 }
 
+void UiElement::SetMode(ColorScheme::Mode mode) {
+  if (mode_ == mode)
+    return;
+  mode_ = mode;
+  OnSetMode();
+}
+
+void UiElement::OnSetMode() {}
+
 }  // namespace vr_shell