VR: Autofill - Remove transparency of the web content

Autofill shouldn't make the content quad transparent.

Bug: 835903
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_vr
Change-Id: I33a3dcd02c526a24beccd3d5504fc26840e734fa
Reviewed-on: https://chromium-review.googlesource.com/1024283Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Commit-Queue: Amirhossein Simjour <asimjour@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552787}

chrome/browser/vr/ui_scene_creator.cc

@@ -888,7 +888,9 @@ void UiSceneCreator::Create2dBrowsingSubtreeRoots() {
   element->set_bounds_contain_children(true);
   element->SetTransitionedProperties({OPACITY});
   element->AddBinding(
-      VR_BIND(bool, Model, model_, !model->hosted_platform_ui.hosted_ui_enabled,
+      VR_BIND(bool, Model, model_,
+              !model->hosted_platform_ui.hosted_ui_enabled ||
+                  model->hosted_platform_ui.floating,
               UiElement, element.get(),
               view->SetOpacity(value ? 1.0 : kModalPromptFadeOpacity)));
   scene_->AddUiElement(k2dBrowsingOpacityControlForUpdateKeyboardPrompt,