[vr] Fix opacity inheritance

This CL fixes a bug in UiElement::UpdateInheritedProperties where we
were accidentally pulling the parent's local, not combined opacity.

Bug: 767559
Change-Id: Ie8092299ec32229f73e89172b352959e75b7bfd6
Reviewed-on: https://chromium-review.googlesource.com/676664Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503541}

chrome/browser/vr/elements/ui_element.cc

@@ -329,7 +329,7 @@ void UiElement::UpdateInheritedProperties() {
 
   if (parent_) {
     inheritable.ConcatTransform(parent_->inheritable_transform());
-    set_computed_opacity(computed_opacity() * parent_->opacity());
+    set_computed_opacity(computed_opacity() * parent_->computed_opacity());
   }
 
   transform.ConcatTransform(inheritable);

chrome/browser/vr/ui_scene_manager_unittest.cc

@@ -28,9 +28,6 @@ using TargetProperty::TRANSFORM;
 using TargetProperty::OPACITY;
 
 namespace {
-std::set<UiElementName> kBackgroundElements = {
-    kBackgroundFront, kBackgroundLeft, kBackgroundBack,
-    kBackgroundRight, kBackgroundTop,  kBackgroundBottom};
 std::set<UiElementName> kFloorCeilingBackgroundElements = {
     kBackgroundFront, kBackgroundLeft,   kBackgroundBack, kBackgroundRight,
     kBackgroundTop,   kBackgroundBottom, kCeiling,        kFloor};
@@ -263,7 +260,7 @@ TEST_F(UiSceneManagerTest, WebVrAutopresentedInsecureOrigin) {
   manager_->SetWebVrMode(true, false);
   // Initially, the security warnings should not be visible since the first
   // WebVR frame is not received.
-  auto initial_elements = kBackgroundElements;
+  auto initial_elements = std::set<UiElementName>();
   initial_elements.insert(kSplashScreenText);
   initial_elements.insert(kSplashScreenBackground);
   VerifyElementsVisible("Initial", initial_elements);
@@ -294,7 +291,7 @@ TEST_F(UiSceneManagerTest, WebVrAutopresented) {
   manager_->SetWebVrSecureOrigin(true);
 
   // Initially, we should only show the splash screen.
-  auto initial_elements = kBackgroundElements;
+  auto initial_elements = std::set<UiElementName>();
   initial_elements.insert(kSplashScreenText);
   initial_elements.insert(kSplashScreenBackground);
   VerifyElementsVisible("Initial", initial_elements);