[vr] If padding doesn't affect bounds, nor should it centering/anchoring

Previously, if a shadow had set anchoring or centering, the size of the
shadow would have affected the positioning. This should not be true;
centering and anchoring should proceed as if there were no shadow at
all. We have the property bounds_contain_padding that captures this
concept in other contexts and this CL applies that notion to centering
and anchoring.

Bug: 834432
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: I79465951c50374174710d7d76dc70d3e9cd6bdea
Reviewed-on: https://chromium-review.googlesource.com/1019600
Commit-Queue: Ian Vollick <vollick@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552080}

chrome/browser/vr/elements/ui_element.cc

@@ -319,13 +319,21 @@ gfx::SizeF UiElement::size() const {
 void UiElement::SetLayoutOffset(float x, float y) {
   if (x_centering() == LEFT) {
     x += size_.width() / 2;
+    if (!bounds_contain_padding_)
+      x -= left_padding_;
   } else if (x_centering() == RIGHT) {
     x -= size_.width() / 2;
+    if (!bounds_contain_padding_)
+      x += right_padding_;
   }
   if (y_centering() == TOP) {
     y -= size_.height() / 2;
+    if (!bounds_contain_padding_)
+      y += top_padding_;
   } else if (y_centering() == BOTTOM) {
     y += size_.height() / 2;
+    if (!bounds_contain_padding_)
+      y -= bottom_padding_;
   }
 
   if (x == layout_offset_.at(0).translate.x &&
@@ -851,14 +859,22 @@ void UiElement::LayOutChildren() {
     float x_offset = 0.0f;
     if (child->x_anchoring() == LEFT) {
       x_offset = -0.5f * size().width();
+      if (!child->bounds_contain_padding())
+        x_offset += left_padding_;
     } else if (child->x_anchoring() == RIGHT) {
       x_offset = 0.5f * size().width();
+      if (!child->bounds_contain_padding())
+        x_offset -= right_padding_;
     }
     float y_offset = 0.0f;
     if (child->y_anchoring() == TOP) {
       y_offset = 0.5f * size().height();
+      if (!child->bounds_contain_padding())
+        y_offset -= top_padding_;
     } else if (child->y_anchoring() == BOTTOM) {
       y_offset = -0.5f * size().height();
+      if (!child->bounds_contain_padding())
+        y_offset += bottom_padding_;
     }
     child->SetLayoutOffset(x_offset, y_offset);
   }

chrome/browser/vr/elements/ui_element_unittest.cc

@@ -123,6 +123,84 @@ TEST(UiElement, IgnoringAsymmetricPadding) {
   EXPECT_VECTOR3DF_EQ(gfx::Point3F(), p);
 }
 
+TEST(UiElement, BoundsContainPaddingWithAnchoring) {
+  // If an element's bounds do not contain padding, then padding should be
+  // discounted when doing anchoring.
+  auto parent = std::make_unique<UiElement>();
+  parent->SetSize(1.0, 1.0);
+
+  auto child = std::make_unique<UiElement>();
+  child->SetSize(0.5, 0.5);
+  child->set_padding(2.0, 2.0);
+  child->set_bounds_contain_padding(false);
+
+  auto* child_ptr = child.get();
+
+  parent->AddChild(std::move(child));
+
+  struct {
+    LayoutAlignment x_anchoring;
+    LayoutAlignment y_anchoring;
+    gfx::Point3F expected_position;
+  } test_cases[] = {
+      {LEFT, NONE, {-0.5, 0, 0}},
+      {RIGHT, NONE, {0.5, 0, 0}},
+      {NONE, TOP, {0, 0.5, 0}},
+      {NONE, BOTTOM, {0, -0.5, 0}},
+  };
+
+  for (auto test_case : test_cases) {
+    child_ptr->set_x_anchoring(test_case.x_anchoring);
+    child_ptr->set_y_anchoring(test_case.y_anchoring);
+    parent->DoLayOutChildren();
+    gfx::Point3F p;
+    child_ptr->LocalTransform().TransformPoint(&p);
+    EXPECT_VECTOR3DF_EQ(test_case.expected_position, p);
+  }
+}
+
+TEST(UiElement, BoundsContainPaddingWithCentering) {
+  // If an element's bounds do not contain padding, then padding should be
+  // discounted when doing centering.
+  auto parent = std::make_unique<UiElement>();
+  parent->SetSize(1.0, 1.0);
+
+  auto child = std::make_unique<UiElement>();
+  child->set_padding(2.0, 2.0);
+  child->set_bounds_contain_padding(false);
+  child->set_bounds_contain_children(true);
+
+  auto grandchild = std::make_unique<UiElement>();
+  grandchild->SetSize(0.5, 0.5);
+
+  child->AddChild(std::move(grandchild));
+
+  auto* child_ptr = child.get();
+
+  parent->AddChild(std::move(child));
+
+  struct {
+    LayoutAlignment x_centering;
+    LayoutAlignment y_centering;
+    gfx::Point3F expected_position;
+  } test_cases[] = {
+      {LEFT, NONE, {0.25, 0, 0}},
+      {RIGHT, NONE, {-0.25, 0, 0}},
+      {NONE, TOP, {0, -0.25, 0}},
+      {NONE, BOTTOM, {0, 0.25, 0}},
+  };
+
+  for (auto test_case : test_cases) {
+    child_ptr->set_x_centering(test_case.x_centering);
+    child_ptr->set_y_centering(test_case.y_centering);
+    child_ptr->DoLayOutChildren();
+    parent->DoLayOutChildren();
+    gfx::Point3F p;
+    child_ptr->LocalTransform().TransformPoint(&p);
+    EXPECT_VECTOR3DF_EQ(test_case.expected_position, p);
+  }
+}
+
 TEST(UiElement, BoundsContainScaledChildren) {
   auto a = std::make_unique<UiElement>();
   a->SetSize(0.4, 0.3);