VR: Move platform toast toward the bottom of the content

This change puts the toast over content, near the bottom, in a position
just above where a downloading snackbar appears.  It also removes the
linear layout that previously held more than one toast.

BUG=828515

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;master.tryserver.chromium.linux:linux_vr;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Iab15c457261e9887940c69140c9af607eb18f1cd
Reviewed-on: https://chromium-review.googlesource.com/998404Reviewed-by: Biao She <bshe@chromium.org>
Commit-Queue: Christopher Grant <cjgrant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548776}

chrome/browser/vr/ui_scene_constants.h

@@ -82,6 +82,7 @@ static constexpr float kToastYPaddingDMM = 0.02f;
 static constexpr float kToastCornerRadiusDMM = 0.004f;
 static constexpr float kToastTextFontHeightDMM = 0.023f;
 static constexpr int kToastTimeoutSeconds = 6;
+static constexpr float kPlatformToastVerticalOffset = 0.5f;
 
 static constexpr float kSplashScreenTextDistance = 2.5f;
 static constexpr float kSplashScreenTextFontHeightDMM = 0.05f;

chrome/browser/vr/ui_scene_creator.cc

@@ -2952,25 +2952,25 @@ void UiSceneCreator::CreateWebVrOverlayElements() {
 }
 
 void UiSceneCreator::CreateToasts() {
-  auto layout = Create<LinearLayout>(kNone, kPhaseNone, LinearLayout::kLeft);
-  layout->set_contributes_to_parent_bounds(false);
-  layout->set_y_anchoring(TOP);
-  layout->SetTranslate(0, kIndicatorVerticalOffset, kIndicatorDistanceOffset);
-  layout->set_margin(kWebVrPermissionMargin);
-
   auto platform_toast = CreateTextToast(
       kPlatformToastTransientParent, kPlatformToast, model_, base::string16());
+  platform_toast->set_contributes_to_parent_bounds(false);
+  platform_toast->set_y_anchoring(BOTTOM);
+  platform_toast->set_y_centering(TOP);
+  platform_toast->SetTranslate(0, kPlatformToastVerticalOffset,
+                               kIndicatorDistanceOffset);
   platform_toast->AddBinding(std::make_unique<Binding<const PlatformToast*>>(
       VR_BIND_LAMBDA([](Model* m) { return m->platform_toast.get(); },
                      base::Unretained(model_)),
       VR_BIND_LAMBDA(
           [](TransientElement* t, const PlatformToast* const& value) {
-            SetVisibleInLayout(t, value);
+            t->SetVisible(value);
             if (value) {
               t->RefreshVisible();
             }
           },
           base::Unretained(platform_toast.get()))));
+
   Text* text_element =
       static_cast<Text*>(platform_toast->GetDescendantByType(kTypeToastText));
   DCHECK(text_element);
@@ -2984,9 +2984,8 @@ void UiSceneCreator::CreateToasts() {
             }
           },
           base::Unretained(text_element))));
-  layout->AddChild(std::move(platform_toast));
 
-  scene_->AddUiElement(k2dBrowsingContentGroup, std::move(layout));
+  scene_->AddUiElement(k2dBrowsingContentGroup, std::move(platform_toast));
 }
 
 }  // namespace vr