Adjust VRShell floor grid to align with users physical floor.

If GVR reports a floor offset from the current tracking origin the floor
grid will be adjusted to render at the same offset. This should help
user comfort when using standalone devices.

Bug: 845225
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: I08bd081087f4f6528ec8200ee424d08f9bf9f059
Reviewed-on: https://chromium-review.googlesource.com/1067541
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561690}

chrome/browser/android/vr/vr_shell_gl.cc

@@ -1602,6 +1602,13 @@ void VrShellGl::DrawIntoAcquiredFrame(int16_t frame_index,
                  &render_info_);
   ui_->OnProjMatrixChanged(render_info_.left_eye_model.proj_matrix);
 
+  // This may change when the floor height changes so it's computed every frame.
+  gvr::Value floor_height;
+  if (gvr_api_->GetCurrentProperties().Get(GVR_PROPERTY_TRACKING_FLOOR_HEIGHT,
+                                           &floor_height)) {
+    ui_->SetFloorHeight(floor_height.f);
+  }
+
   // Content quad can't have transparency when using the quad layer because we
   // can't blend with the quad layer.
   bool use_quad_layer = ui_->IsContentVisibleAndOpaque();

chrome/browser/vr/model/model.h

@@ -60,6 +60,7 @@ struct Model {
   std::vector<TabModel> incognito_tabs;
   bool incognito_tabs_view_selected = false;
   bool create_tabs_view = false;
+  float floor_height = 0.0f;
 
   // WebVR state.
   WebVrModel web_vr;

chrome/browser/vr/ui.cc

@@ -184,6 +184,10 @@ void Ui::OnUiRequestedNavigation() {
   model_->pop_mode(kModeEditingOmnibox);
 }
 
+void Ui::SetFloorHeight(float floor_height) {
+  model_->floor_height = floor_height;
+}
+
 void Ui::SetSpeechRecognitionEnabled(bool enabled) {
   if (enabled) {
     model_->speech.recognition_result.clear();

chrome/browser/vr/ui.h

@@ -159,6 +159,7 @@ class Ui : public BrowserUiInterface, public KeyboardUiInterface {
   void OnContentBoundsChanged(int width, int height);
   void OnPlatformControllerInitialized(PlatformController* controller);
   void OnUiRequestedNavigation();
+  void SetFloorHeight(float floor_height);
 
   Model* model_for_test() { return model_.get(); }
 

chrome/browser/vr/ui_scene_creator.cc

@@ -900,6 +900,9 @@ std::unique_ptr<Grid> CreateGrid(Model* model, UiElementName name) {
   grid->set_gridline_count(kFloorGridlineCount);
   grid->SetGridColor(model->color_scheme().floor_grid);
   grid->set_focusable(false);
+  grid->AddBinding(VR_BIND(
+      float, Model, model, model->floor_height, Grid, grid.get(),
+      view->SetTranslate(0, value ? value : -kSceneHeight / 2.0f, 0.0)));
   return grid;
 }