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

chrome/browser/android/vr_shell/vr_shell_gl.cc

Index: chrome/browser/android/vr_shell/vr_shell_gl.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.cc b/chrome/browser/android/vr_shell/vr_shell_gl.cc
index 731f6510a948599781dd6df713c059a134e4cd1b..a981ffba66bbee6b8466f392e9f2ef9832e4d0a0 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.cc
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.cc
@@ -1114,7 +1114,7 @@ void VrShellGl::DrawWorldElements(const vr::Mat4f& head_pose) {
     glEnable(GL_DEPTH_TEST);
     glDepthMask(GL_TRUE);
 
-    const SkColor backgroundColor = scene_->GetBackgroundColor();
+    const SkColor backgroundColor = scene_->GetWorldBackgroundColor();
     glClearColor(SkColorGetR(backgroundColor) / 255.0,
                  SkColorGetG(backgroundColor) / 255.0,
                  SkColorGetB(backgroundColor) / 255.0,