VR: Clean up selection of hit-testable elements.

This furthers previous lifecycle framework cleanup, and fixes an
outstanding technical-debt bug in the process.

BUG=768079
R=ymalik

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: I6743ed68e16f437d68ccc27849f3694af347617a
Reviewed-on: https://chromium-review.googlesource.com/1015645
Commit-Queue: Christopher Grant <cjgrant@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553664}

chrome/browser/android/vr/vr_shell_gl.cc

@@ -1658,7 +1658,7 @@ void VrShellGl::DrawIntoAcquiredFrame(int16_t frame_index,
 
   std::vector<const UiElement*> overlay_elements;
   if (is_webvr_frame) {
-    overlay_elements = ui_->scene()->GetVisibleWebVrOverlayElementsToDraw();
+    overlay_elements = ui_->scene()->GetWebVrOverlayElementsToDraw();
   }
 
   TRACE_COUNTER1("gpu", "VR overlay element count", overlay_elements.size());

chrome/browser/vr/ui_input_manager.cc

@@ -60,14 +60,12 @@ bool IsScrollEvent(const GestureList& list) {
 void HitTestElements(UiScene* scene,
                      ReticleModel* reticle_model,
                      HitTestRequest* request) {
-  std::vector<const UiElement*> elements = scene->GetVisibleElements();
+  std::vector<const UiElement*> elements = scene->GetElementsToHitTest();
   std::vector<const UiElement*> sorted =
       UiRenderer::GetElementsInDrawOrder(elements);
 
   for (const auto* element : base::Reversed(sorted)) {
-    if (!element->IsHitTestable()) {
-      continue;
-    }
+    DCHECK(element->IsHitTestable());
 
     HitTestResult result;
     element->HitTest(*request, &result);

chrome/browser/vr/ui_renderer.cc

@@ -22,7 +22,7 @@ UiRenderer::~UiRenderer() = default;
 // itself correctly.
 void UiRenderer::Draw(const RenderInfo& render_info) {
   glEnable(GL_CULL_FACE);
-  DrawUiView(render_info, scene_->GetVisibleElementsToDraw());
+  DrawUiView(render_info, scene_->GetElementsToDraw());
 }
 
 void UiRenderer::DrawWebVrOverlayForeground(const RenderInfo& render_info) {
@@ -32,7 +32,7 @@ void UiRenderer::DrawWebVrOverlayForeground(const RenderInfo& render_info) {
 
   glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
   glClear(GL_COLOR_BUFFER_BIT);
-  DrawUiView(render_info, scene_->GetVisibleWebVrOverlayElementsToDraw());
+  DrawUiView(render_info, scene_->GetWebVrOverlayElementsToDraw());
 }
 
 void UiRenderer::DrawUiView(const RenderInfo& render_info,

chrome/browser/vr/ui_scene.cc

@@ -212,9 +212,10 @@ std::vector<UiElement*>& UiScene::GetAllElements() {
   return all_elements_;
 }
 
-UiScene::Elements UiScene::GetVisibleElements() {
+UiScene::Elements UiScene::GetElementsToHitTest() {
   return GetVisibleElementsWithPredicate(
-      root_element_.get(), [](UiElement* element) { return true; });
+      root_element_.get(),
+      [](UiElement* element) { return element->IsHitTestable(); });
 }
 
 UiScene::MutableElements UiScene::GetVisibleElementsMutable() {
@@ -222,7 +223,7 @@ UiScene::MutableElements UiScene::GetVisibleElementsMutable() {
       root_element_.get(), [](UiElement* element) { return true; });
 }
 
-UiScene::Elements UiScene::GetVisibleElementsToDraw() {
+UiScene::Elements UiScene::GetElementsToDraw() {
   return GetVisibleElementsWithPredicate(
       root_element_.get(), [](UiElement* element) {
         return element->draw_phase() == kPhaseForeground ||
@@ -231,7 +232,7 @@ UiScene::Elements UiScene::GetVisibleElementsToDraw() {
       });
 }
 
-UiScene::Elements UiScene::GetVisibleWebVrOverlayElementsToDraw() {
+UiScene::Elements UiScene::GetWebVrOverlayElementsToDraw() {
   auto* webvr_root = GetUiElementByName(kWebVrRoot);
   return GetVisibleElementsWithPredicate(webvr_root, [](UiElement* element) {
     return element->draw_phase() == kPhaseOverlayForeground;

chrome/browser/vr/ui_scene.h

@@ -61,10 +61,9 @@ class UiScene {
   typedef std::vector<UiElement*> MutableElements;
 
   std::vector<UiElement*>& GetAllElements();
-  Elements GetVisibleElements();
-  MutableElements GetVisibleElementsMutable();
-  Elements GetVisibleElementsToDraw();
-  Elements GetVisibleWebVrOverlayElementsToDraw();
+  Elements GetElementsToHitTest();
+  Elements GetElementsToDraw();
+  Elements GetWebVrOverlayElementsToDraw();
 
   float background_distance() const { return background_distance_; }
   void set_background_distance(float d) { background_distance_ = d; }
@@ -81,6 +80,8 @@ class UiScene {
  private:
   void InitializeElement(UiElement* element);
 
+  MutableElements GetVisibleElementsMutable();
+
   std::unique_ptr<UiElement> root_element_;
 
   float background_distance_ = 10.0f;

chrome/browser/vr/ui_scene_unittest.cc

@@ -190,10 +190,10 @@ TEST(UiScene, NoViewportAwareElementWhenNoVisibleChild) {
   element->SetDrawPhase(kPhaseOverlayForeground);
   child->AddChild(std::move(element));
 
-  EXPECT_FALSE(scene.GetVisibleWebVrOverlayElementsToDraw().empty());
+  EXPECT_FALSE(scene.GetWebVrOverlayElementsToDraw().empty());
   child->SetVisible(false);
   scene.OnBeginFrame(MsToTicks(0), kStartHeadPose);
-  EXPECT_TRUE(scene.GetVisibleWebVrOverlayElementsToDraw().empty());
+  EXPECT_TRUE(scene.GetWebVrOverlayElementsToDraw().empty());
 }
 
 TEST(UiScene, InvisibleElementsDoNotCauseAnimationDirtiness) {